There are many, each with their own methodology – and sets of nuances & headaches.
Here are some terms to research: NDI, SRT, Web RTC.
If you use skype for a single caller, it has HD output via NDI that you can record with a app like OBS, vMix, WireCast, etc. Microsoft Teams also supports NDI out and you can capture each person (upt to 9) as a full HD stream individually in up to 1080p. vMix has its own utility called vMixCall – web usage is 720p, if they too have vMix you can do 1080p.
Everything depends on the quality of gear on the callers end and their abilty to use it. A 1080p webcam can look good with decent lighting and they’ll need a good mic too. Along with a wired internet connection. Your machine will need to be fairly robust too with a solid GPU.
If you are looking for a great signal, look at HDMI/SDI to SRT encoders that you receive the signal.
Don’t overlook the idea of you directing things via zoom and they record on their phone and send a file to you.