Indoor Training - Adjusting Workout Intensity

In the past I trained indoors with software like Zwift, Trainer Road etc. I'd like to switch to my Edge 1050 because in theory it does everything that I need.

However, the one thing that I am missing and just cannot find is how to systematically adjust the workout intensity in % for the whole workout while training.

My workout files have ranges for target power. Logically, the edge 1050 aims for the middle of the range, which is fine. But I want to adjust this during training according to how I feel.

Yes, I know I can adjust the target power in a certain interval but this way one needs to do it during training for every interval again and again. This does not make sense. Especially if you have like 20s sprints and need to adjust at the beginning of every interval which takes like 5-10s...

What I am looking for is what every training app has: a workout intensity control in percent that applies a bias for the whole workout. For comparison see: https://support.zwift.com/en_us/adjusting-your-workout-intensity-B1PftWd1g

Is there any way to do it?