Agreed with the advice around using resistance mode.
Fun fact: any duration above threshold will eventually elicit VO2max, but you also have to layer in the other energy systems especially towards the front half of the workout.
These intervals get progressively more “aerobic” as you do more of them (as you deplete anaerobic work capacity), so you could be working at a lower power over time but still be eliciting the desired VO2max response.
So as long as you are going as hard as you can for the stated interval duration towards the end of the workout, don’t worry so much about the power unless is dramatically off target.
(Note: this only applies to VO2max workouts)