It is definitely still a thing so certainly should be there (as you know).
I've just gone to the phone app on my S24 Ultra and clicked on 3 dots top right and WiFi calling is about two thirds of the way down.
Might need to check in with your network if they provision it but not sure you should need to really.
I am not employed by Samsung nor do I receive any remuneration as a Samsung Members Star.
My device is an S25 Ultra.