Number of participants for group call is up to 8 for Whatsapp. Is group call P2P or through Whatsapp server like Zoom due to number of participants?
The answer to your question can be found here: https://www.whatsapp.com/security/
Although it does not say it explicitly that it is not point-to-point. It can be inferred from the "Speak freely" and "Security by default" sections of that page where it says "WhatsApp calls are end-to-end encrypted so WhatsApp and third parties can't listen to them." Just so you don't get confused, End to End encryption does not mean Point to Point. Zoom is end-to-end encryption as well (although there are problems in the type of encryption they use).
Everything in Whatsapp utilizes a server. The amount of overhead that would occur if Whatsapp was P2P would be high. Also there will be very high CPu usage as there would be multiple encrypted connections happening simultaneously, which would mean high battery usage. Thus Whatsapp is not P2P but utilizes a server.