No, the GoPro Hero12 Black is not compatible with the Lexar Professional 2000x 128GB SD UHS-II.
GoPro HERO12 Black has a microSD-only card slot. Its own product page confirms only microSD card compatibility -- a full-size SD card is physically larger than a microSD card and does not fit this slot (the reverse of the more common microSD-via-adapter case: here there is no adapter that shrinks a full-size card down to fit).
What works instead
See all compatible camera for the GoPro Hero12 Black →“Memory Storage microSD 1x microSD™ rated class A2 V30 or higher”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)