What? No.
A Moon Elf is an elf.
A Wood elf is an elf.
They can make little Mood Elfs. They're not separate species and subrace does not imply that.
Then. It's only a no-no because the Bretons are in fact, smarter than the Nords. But Nords are stronger and get Frost Resist. And the Redguards have a different skin color. They're arguahly the best fighters of all.
And yeah, they look a little different, but that's not even a thing in BG3 because appearance is separate from those atrributes. You can make you Duergar look like a Shield Dwarf.
