Is there any truth to the "myth" that if you have been muscular and heavier for a long time(with drugs) that the body is forced to re/set its balance and you would end up a bigger version of yourself?
No. This is a bullshit myth, unless you used steroids from the moment you started lifting to get your beginner gains. A lot of people will mistaken this for steroid gains when all they had to so was touch a weight there first year and grow like a weed.
You will hold your natural build along with whatever muscle you put on before gear. You will keep some muscle after the steroid use, but most of it will be gone
Most of the muscle and weight you will lose off steroids wont be noticable at first or even months after you come off. It will be alow.and gradual. Your friends will start asking if you are cutting weight, your strength will gradually go down along with your once tight some XL will be baggy yet again. Slowly you will start realize you are smaller, but still be in denial of your hard gains you made while on steroids. Eventually you will.notice the scale saying you weigh twenty to thirty pounds and once again you are back at square one. Looking like a natural, and what you used to look like before the steroid abuse.
You wont keep your gains.