Volodymir Zelensky's presidential mandate has formally expired on May 19, but he remains the president and no new presidential elections were held. This is in accordance with the country's constitute and Ukrainian electoral law, which prohibit holding elections while the country is under martial law (see, e.g., here (in French).)
There are obvious reasons why at the moment this is probably the best for Ukraine, and the majority of Ukrainians would probably back Zelensky anyhow. I wonder however, whether there are any safeguards for preventing the Ukrainian president from becoming a dictator, if the war drags on for a another decade or two? Have any western governments asked Ukraine to commit to a specific deadline where the elections would have to be held anyway?