Due to circumstances that I will never fully expand on, I had to un-transition. I have also met a couple of people who had gone on HRT and then decided they were not TS.
My own experience. I had been on HRT for a little over a year. After dropping the hormones I went through a menopause like state for a couple of months. After that things were pretty much back to normal. I have had breasts pretty much for my whole life, HRT just made them a little bigger. I would just bind or wear baggy clothes. If I worked out more they probably would have gone back close to what they were before I started HRT.
The others that I met. You cannot tell they once tried the path of m2f at all. If they had not said anything, I never would have guessed. Neither had a lot of electro done so they were pretty hairy. I saw the chest of one of the guys and it did not look to be anything other than a guy's chest.
YMMV of course, depending on the length and intensity of the hormone treatment. As one of my doctor's put it, "Your body really likes this stuff" so I may be atypical when it comes to these things, I have no idea.