Even if you could convince your management to downlevel you, you're not going to be able to stop juniors coming to you for help or product owners/managers from giving you tasking of a similar level to what they've come to expect.

In my mind there's really only one way to achieve what you're after here. If you're truly ready to exit in pursuit of this new career then go to your management and inform them that you'll be leaving, but offer to continue working for them on a 1099/consultant basis for some number of predetermined hours per week or on the completion of some feature(s) by some date (as long as the time required to deliver by that date aligns with how much you want to work).

If they're receptive make sure you make it clear that they will have no bearing on when/where you perform the work.

Otherwise, try to find another employer to make a similar arrangement with, or apply for very low-efforts jobs (probably at non-tech companies) where you can come in fresh without a reputation of being a high-performer and phone it in.