What about practicing shadow stroke/footwork drills facing a mirror and staying low while doing them? That will strengthen everything you need to stay there and since you are looking in the mirror, you can see any time you start coming up and force yourself to get back down. You are also doing what you need to do in actual play while doing the work you need to to stay low.
There are other strengthening exercises that would benefit you. But something that forces you to do the exact actions you would while playing while taking the ball out of the equation would be very beneficial to developing the HABITS that will allow you to stay low.
On one of these Table Tennis Exercise threads years ago (2015-2017) someone posted video footage of the German National Team working out and it was footage of athletes at different stations doing different and related exercises. Some with bands around their legs while staying low with legs wide and moving side to side. Some going up stairs like that. There were a lot of different stations. That video looked very useful.
From the CNT they showed footage in a different video of the players, low, in a crouch, as if ready to play, and the trainer was throwing balls at the ground near them and they had to footwork to and kick the balls, one ball after the other so they were moving side to side as the balls were being thrown to random places. They were doing all this while staying in a low stance as if at the table.
All of those exercises were hard to describe and the video footage would be worth watching. But.....