DeletedUser115 I think disabling Wi-Fi calling may be a prudent way to reduce attack surface. I briefly started reading up on how the pieces fit together, and it seems as if there are a lot of pieces.
If you live in the U.S. I doubt you can disable VoLTE, though -- the major carriers pretty much require it (I think Verizon has required VoLTE since around 2020). And it seems that carriers worldwide are rolling it out, which I expect will be followed by ending support for legacy voice calls.