What Zelda is Ultimate's Sheik???

[Door Key Pig]

Is her Brawl/Smash 4 elements meaning she's Twilight Princess Zelda?

Or does her Breath of the Wild clothing mean she's a BotW Zelda ala her Brawl design despite not being in Twilight Princess?

Could it be we technically have a Twilight Princess or second BotW character in Smash Ultimate already?

 

[XigmunGothar]

Based on what I know and can tell, Sheik herself and her essential features make her technically a Twilight Princess rep, but they have added Breath of the Wild inspirations. As Sakurai stated, with Zelda being more into research in BotW, I don't think Ultimate Sheik is meant to be her. It's basically a "modernized costume change" plus a new Final Smash. Still, could she be BotW Zelda during her time before/after that game, I don't see why not. It's a cool idea for a next game or DLC or something.
As far as SSBU goes, what I keep seeing others refer to is Link as BotW and Sheik as TP.

 

[Diddy Kong]

Ocarina of Time.