We can see from contact structure  that it has a field called photoURL, but I don't know how I can provide this info.

We can see from create contact api that there's no way we can provide this info, and I don't know how to provide it in the zoho desk website contacts module either.

Edit:

The only way I find can affect this field is through Help Center. But I think it's very important that I can change this filed through Api. Let's assume, we have a Single Page App with ASAP( with no help center), then there will be no way for me to match their avatar in my website in the ASAP.

It's also helpful if jwt based login in ASAP support both name and picture claims. Then when a customer login in ASAP, they can have a name and avatar in the tickets and community tab.