Custom URL (asl_redirect_url)

Hello,

I hope everyone is safe.

I am trying to create a custom URL to change from that:
https://site.com/?s={phrase}
to this:
https://site.com/?redirect_to=random&s={phrase}

I read the notice regarding regarding asl_redirect_url, but I didn’t find more precision about it. Can you explain to me how I can edit the URL the way I described it above?

Thanks.