Russia is a multi-cultural country - it contains 185 different ethnic groups speaking over 100 different languages. Thus it has enough political experience from its own history to know that Russification doesn't really work, and Sovietization offers better results but needs to be gradual. Today, under Putin, Russia follows a mixture of the Russofication and Sovetization policies to deal with multi-culturalism.
As per Article 68 of the Russian constitution - :
The Russian language shall be a state language on the whole territory of the Russian Federation.
The Republics shall have the right to establish their own state languages. In the bodies of state authority and local self-government, state institutions of the Republics they shall be used together with the state language of the Russian Federation.
The Russian Federation shall guarantee to all of its peoples the right to preserve their native language and to create conditions for its study and development.
Despite Russian being the dominant language in Crimea -
Ukranian and Crimean Tatar are also recognized as the official language through the provisions of the above cited Article 68 (2). This has been made official as per Article 3 of the Agreement between the Russian Federation and the Republic of Crimea on the admission of the Republic of Crimea to the Russian Federation and the formation of new subjects within the Russian Federation (translated) which says:
The Russian Federation guarantees to all peoples living in the territories of the Republic of Crimea and the federal city of Sevastopol the right to preserve their native language and create conditions for its study and development.
The official languages of the Republic of Crimea are Russian, Ukrainian and Crimean Tatar.
(Original Russian source - Договор между Российской Федерацией и Республикой Крым о принятии в Российскую Федерацию Республики Крым и образовании в составе Российской Федерации новых субъектов translated to English with Yandex Translate).
However, Russia has also introduced a tweak in their education policy, where in no languages, apart from Russian, is mandatorily taught in schools. This means any Russian Republic cannot force the citizens to also learn the other state language(s) that they officially recognize. Students can only learn these languages if they want to (voluntarily) and only if they have permission from their parents.
"Forcing a person to learn a language that is not their native one is just as unacceptable as reducing the level and time of teaching Russian," the president said ... - Russian minorities fear for languages.
Thus, in the absence of other reliable evidence (so far), we can conclude that Ukranian and Crimean Tatar continue to be taught in annexed Crimea to those who want to learn it.
Russia has also immediately invested in upgrading the education infrastructure in Crimea (to win over the population), and made attempts to ensure that no one's education is disrupted:
With the development of the network of educational organizations carrying out their activities in accordance with Russian laws, there are created new universities and research organizations in the Crimea. According to the Order of the Government of the Russian Federation # 1465 dated on August 4, 2014 there will be created Crimean Federal University named after Vernadsky in the Crimea. It will consist of seven high schools located in the Crimea, and seven research organizations. It is the tenth Federal University of Russia. Crimean Federal University will start its work by 2015. Citizens residing permanently in the Crimea and Sevastopol, are ensured with the continuation of education in the universities of the Russian Federation. There are special quotas for entrants from the Crimea in geographically closely located universities, they are Southern Federal University and the North Caucasus Federal University ... (Source: Management of Enrollment of Students from the Crimea in the Russian University Education Establishments ).
(A Russian propaganda source also claims 200 new kindergartens has been built since Russia took over Crimea).
However, everything isn't rosy for the Ukranians under Russian occupation. The Ukranians fighting Russia have observed with dismay that the switch to the Russian educational systems means that Ukranians in Russian occupied territories will no longer learn "Ukranian government sanctioned" history:
At the same time, the occupation authorities put pressure on educators and school managers to resume work and switch to teaching in Russian and according to Russian standards and textbooks. There is evidence of mandatory retraining for educators who have been deported to Crimea or Russia in order to make them teach in Russian in the future. There are also testimonies of threats against educators and their families in case they refuse to collaborate.
... Russia intends to introduce forced teaching of Russian for the deported people. Lilia Humerova, the head of the science, education and culture committee of the Federation Council of Russia, said that it was a problem that the deported Ukrainian children do not speak Russian “at a sufficient level,” which will prevent them from mastering the Russian education curriculum. According to her, there is a plan to organize summer language courses for these children. There was no mention of whether attendance of these courses would be voluntary.
... In the occupied Crimea ... Ukrainian Literature and History of Ukraine were also removed from the curriculum. In addition, the education system switched from the 12-grade system of evaluation to the 5-grade system. Ukrainian textbooks were removed from use and Russian textbooks were introduced instead. History of Ukraine was replaced in the occupied peninsula with History of Russia taught according to the unified textbooks approved in Russia. 10,500 people graduated from high school in Crimea in 2021.
Higher education was also transformed in Crimea. In particular, the Vernadsky Federal University of Crimea was established in Simferopol in 2014 by merging 7 universities and 7 research institutions; the same year, the Sevastopol State University was also established by merging 7 universities. The curricula switched to Russian standards, and the graduates started receiving diplomas according to Russian state regulations.
(Source: Education in the occupied territories of Ukraine (February 24 – April 30, 2022)).