It’s certainly possible depending on the reasons why you would want to do so.
If it’s a case that you’re having difficulty operating at the higher level to the point where you’re stressed or very uncomfortable, a sympathetic HR would facilitate a reversion.
Be aware though that it would likely inhibit your chances of promotion in the future if the impression is created that you already tried and failed at the higher level.
It’s not really that the job is at a higher level it’s just not the right fit for me. I know it is embarrassing for me going back and that’s what is causing me a lot of stress.
I know it may look bad for my future career but maybe in 3-5 years that will possibly change …
It depends on what you mean by “the right fit”. If it’s a case that you just don’t fancy it, you can still apply to revert but your application won’t be warmly received. If the new role is causing stress ir making you ill, that’s another matter.
You need to weigh up the short term disadvantages of the new role against your longer term ambitions. You won’t always be in the old role anyway.