Both of my sons, both of whom are autistic, have hypotonia. They both have received PT, OT, and Speech. I'm sure that the PT and OT have helped.
My older son is very flexible, pretty much a contortionist, because of his low muscle tone.
Hypotonia does not make you weak, as evidenced by my younger son, but it does affect your coordination, balance, and stamina.
As for me, I was always the least capable student in grammar school or high school gym by a big stretch. I've never been able to ride a bicycle, and I now know that I have a very poor sense of balance. So, while it wasn't something that would be diagnosed fifty+years ago, I suspect I have hypotonia as well.