It's not that unusual for people to pick up e.g. powerlifting past 50 and still get to levels well beyond what most younger adults can lift.
I'm 51, and recently back into powerlifting after many years out of it, and I certainly expect to build back muscle and improving week over week for many years before I can't stem the decline any more, as long as avoid injury or health issues that takes me out of the gym - avoiding time off exercise is the biggest challenge with getting older.
But more than a week and you'll typically need to deload to avoid DOMS. More than a few weeks and it will start taking significant time to work back up, and a lot of injuries happens because people try to rush that recovery and add even more time to that.
If you regularly lose weeks at higher age, it quickly becomes tricky to avoid tipping over into lasting decline.