No microwave I’ve seen has ever actually varied the wattage. It just essentially does pulse width modulation, so 60% power might be on (at full power) for 6 seconds and off for 4 seconds. It averages out to the desired power, but it’s not exactly the same as what it kind of implies.
We just watched “The Trap” last night. There was a major pop concert that ended in time for family dinner time during daylight. In the concert, they were depicted having time to make multiple trips to the merch tables and concessions, and in one of those trips, they talked like it was an intermission to change the stage set between songs.