Accepting traffic only through VPN

Is there a way to force users visiting my site, to have their traffic go through the VPN first (the service)?

I can’t think of any reliable way to do this. Why do you want to implement such a restriction?

Illegal torrenting, you must have a way to proxy them for legal protection/bypass. For example, seems to be hosted on cloudflare, which leads me to ask myself the difference between a VPN and proxy.

I haven’t read the TOS. Torrenting isn’t necessarily illegal, which also begs the question that if I claim my site to be illegal breaks the TOS? I read articles about terrorist sites using cloudflare to remain unblocked too.