A 15 minute city is where everything is available to you within 15 minutes walking, biking, or public transit.
I know Mexico city fits this bill. Playa del carmen as well.
PDC I’d rather avoid. A bit too party tourism, dangerous I found.
Vallarta I’ve been too and almost fits. I enjoyed there.
Puerto Escondido was incredible when I was there. Everything was quiet close, with the exception of one excursion that was a 30 minute to 1 hour drive away.