Yep, although (at least in my experience) it's not enabled by default. I also learnt about VoWiFi (also called "WiFi Calling") that allows you using WiFi for calling, including when you're abroad or you don't even have phone signal.

Support for VoWiFi is a bit weird. Some operators don't allow it outside of your region (for example, the EU), some others will allow it and even bill you as if it were a local call made from your country.

Also, although it's in theory made only for working through WiFi, seems like if you have a second SIM or eSIM with a data plan (for example, a travel SIM local for the country you're on vacations) and some combination of phone and/or operators, it can use the second SIM as the data provider for WiFi Calling.

Not for everyone in many places. Many carriers still only allow VoLTE for a limited alow-list of phone models. Any customers of those with less popular models still gets dropped to 3G calls.