In general, body hair will reduce slightly on hrt. It's still there, but in particular I saw a lot less growth for chest hair. If laser works for your skin/hair color combos at a practioner near you, I found it very effective and tolerable. Otherwise I use a safety razor for everything else. Once you're good with it, it's a very close and low irritation save.
For facial hair, almost everybody will see no effect with hrt. New growth (as in fully new follicles) should stop, but any existing hair will need to be removed if you want a smooth face all the time. I did laser for some initial clearing and now am doing electrolysis to finish up.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8213007/
Here's one of the more recent meta analysis papers on it. When people who detransition are asked, the majority of the cite external factors like the ones here.