@aiv4r yes, that’s the way to go!
I always ask my athletes and myself, how quick and how many repetitions were run in the last successful intervall session and how the feeling was the days after. That will be the initial target for the beginning, where RPE does not work yet because everything feels easy. Mostly this prediction over pace from past workouts or races is already very close to what one is capable of at the moment and minor adjustments then come over RPE. The feeling for RPE, one learns over time. But as in ever other sport, experience is key.