The Adventurers League FAQ addresses a question about exactly this topic: reskinning races. You can find the latest version in the "D&D Adventurers League DM & Player Pack" on DMsGuild; the current version as of this answer is FAQ v9.1.
The relevant guidance appears on page 6 of that version of the document. You can also find the same answer on page 7 of the FAQ v9.0 PDF on Wizards of the Coast's website. (As indicated by the changelog for v9.1, the update adds some other sections that don't appear in v9.0, but the guidance on this topic is unchanged.)
In the "Races & Classes" section, below the heading "Reskinning Races", it states:
You may reskin your race (playing a rare elf subrace, for example) if you choose, but have the traits of a normally available subrace (high elf, etc.); the character creation process doesn’t change. Your DM may disallow this if they feel it inappropriate.
Ultimately, as long as you're just reflavoring the race without changing any mechanics, the DM can choose to allow or disallow your proposed reflavoring of the race. (Any mechanical changes based on your reflavoring would not be allowed.)