Star Trek: Strange New Worlds

The Human to Vulcan/Romulon transformation was done before in the original series.
IIRC, all TOS transformations were makeup alterations limited to appearance changes. Subsequent Star Treks (in real time, not in stardate) engaged in surgical alterations of appearance.

More recently are we seeing temporary genetic alterations of appearance (Strange New Worlds S1E1).

Spock has lost control of his emotions several times (making him more Romulan than human). The SNW episode Charades (S2E5) is the first time a comprehensive Vulcan to human transition was made.

AFAIK, this is the first instance where a full racial and cultural change from human to Vulcan is achieved (although we haven't seen them bleed green blood yet).
 

Star Trek: Lower Decks

THE BOYS are back.