Ask for one thing
“Prove who you are” is a demand. “Could you confirm you’re a real person before we meet?” is a request with an edge to it and an obvious way to say yes. Decide the one thing you need and ask for that.
Send a link, not a list of instructions
On Realr you create a request and send the link in the chat you are already in. The other person opens it in a browser. They do not need an account to see what is being asked.
Let them choose
They decide what to share, and nothing is shared unless they tick it. Their documents and contact details do not travel with the answer. This is what makes it reasonable to ask a stranger at all.
Offer yours
Send your own link with the request. It turns a test into an exchange, and it answers the question they are probably about to ask you.
If they say no
They may have a good reason. They may also not be who they say. You do not need to work out which; you only need to decide whether to go ahead without the check.