Summon used to be included in Enhanced Autopilot but I think they moved it to FSD in 2019 or so.
We tested out the double-tap parking a couple of times but never used it regularly. With the S & X, there's an option to require a "continuous press" on the keyfob and it turns the double-tap park functionality on/off as well. We enabled continuous press after the puppies (in the house) got ahold of my key fob once while I was in the garage and started to summon my S.
We do still use the manual summon option from time to time on the S, 3 and Y to back the car out of the garage but never really rely on the double-tap method.
We haven't tried the double-tap park on the 3 or Y. Might go try that out today, if possible.