Yes, you can make the flag of your new nation "whatever [you] wanted", see Pan-African flag
(The red, black, and green Pan-African flag designed by the UNIA in 1920.)
The Pan-African flag—also known as the UNIA flag, Afro-American flag,
Black Liberation Flag and various other names—is a tri-color flag
consisting of three equal horizontal bands of (from top down) red,
black and green. The Universal Negro Improvement Association and
African Communities League (UNIA-ACL) formally adopted it on August
13, 1920 in Article 39 of the Declaration of the Rights of the Negro
Peoples of the World, during its month-long convention at Madison
Square Garden in New York City. Variations of the flag can and have
been used in various countries and territories in Africa and the
Americas to represent Pan-Africanist ideologies. Several Pan-African
organizations and movements have often employed the emblematic
tri-color scheme in various contexts.
The flag was created in 1920 by members of UNIA in response to the
enormously popular 1900 coon song "Every Race Has a Flag but the
Coon".which has been cited as one of the three songs that "firmly
established the term coon in the American vocabulary". In a 1927
report of a 1921 speech appearing in the Negro World weekly newspaper,
Marcus Garvey was quoted as saying:
Show me the race or the nation without a flag, and I will show you a
race of people without any pride. Aye! In song and mimicry they have
said, "Every race has a flag but the coon." How true! Aye! But that
was said of us four years ago. They can't say it now....
The Universal Negro Catechism, published by the UNIA in 1921, refers
to the colors of the flag meaning:
Red is the color of the blood which men must shed for their redemption
and liberty; black is the color of the noble and distinguished race to
which we belong; green is the color of the luxuriant vegetation of our
According to the UNIA as of recent; the three Pan-African colors on
the flag represent:
- red: the blood that unites all people of Black African ancestry, and shed for liberation;
- black: black people whose existence as a nation, though not a nation-state, is affirmed by the existence of the flag; and
- green: the abundant natural wealth of Africa.
Derivatives of the Pan-African flag include
Saint Kitts and Nevis
Historically, flag and seal design has a substantial degree of heraldry involved, see Does a description of the original design for the Great Seal of the United States by Simitiere survive? There is also the practical matter of not having a flag that can be mistaken for another nations' flag, or, for that matter, surrender, which was one of the considerations of the Confederate States of America national flag design, see Did the Confederate States of America ever officially adopt William T. Thompson's descriptions of the CSA national flag?.
From a political and historical perspective, composing and leaving a detailed description of the flag on the record is just as important as the distinctiveness of the flag; for the purpose of settling any potential controversies or disputes as to the meaning and original intent of the designer of the flag.