I don't think so. The handshake agreement is probably against the rules and something all the writers say MLB will scrutinize. I think the Lindor comparison is correct, but Lindor has played three seasons, and averaged 5+ WAR (even with a shorter rookie year). I think Ohtani will also have to play three seasons - but at least two - before he gets his extension, just to make it look kosher.
Certainly a handshake agreement could still factor all of that in. Though it would obviously still look bad, if, say, he was only a three WAR players and the Yankees still extended him for three-years $100 million after 2020. And if that would be allowed, then sure, they may as well just let him sign the deal you propose next year.