2003 Ford F150 with 200K miles transmission question

Just purchased vehicle from friend - it runs great but transmission fluid probably has never been changed. Transmission runs well … but … should I do a transmission flush with new filter or “let a sleeping dog lie”?

Do a transmission drain with filter change. Not a flush.

At 200K, do a filter and pan cleaning and then full fluid exchange.

What Tardis wrote and be sure to use the fluid that is called for!