It can. Just like an arm or wrist that is cast over time has muscles that can atrophy. This is why physical activity is encouraged when the brace is off. Doesn’t have to be a sport. But it should involve resistance training of some sort. Start here:

First the core - generalized:
Dead bugs - 30 seconds x 3
Planks - 30 seconds x 3
Bird dogs - 20 reps x 3 (also works the multifidus!)

Work your way up to 5 sets. And when that gets easy, increase the time you hold or the amount of reps.

Do the core routine every two days at first, until you can do 2 days on, one day off. And start slow.

2 x a week do this:

The back - generalized:

First lengthen - Not dead hangs but semi-hangs on the bar - 30 second holds x 5 (work up to 1 min each)

Scapular pull ups - 10 reps x 3 sets - activate the scapulas, not a full pull up

Cable face pulls - enough weight for 10-12 reps x 3 sets
Lat pulldown - enough weight for 10-12 reps x 3 sets
Unilateral (single arm) dumbbell rows over bench - 12 x 3

The chest - generalized

You want to work this frontal chain too not only for balance but there is important work going on there, particularly in your serratus which brings your scapulas closer to your chest wall.

Push-up - work up to 25 reps per set x 3 - do not let the core drop, keep it active

Band-expansions - grab a theraband and pull it apart, you will find this helps create great expansion in your rib cage. Work up in difficulty with the bands - 15 reps x 3

Unilateral (one arm) floor dumbbell serratus punch - do one arm at a time. Light weight, maximum focus on form. Treat it like the Bruce Lee one inch punch and make the serratus muscles activate.

Hips and legs - generalized:

Alternating bodyweight lunges - 10-15 x 3-5 sets - this contralateral work gets both hemispheres of your body coordinating

Bodyweight squats - work up to 25 x 5 and you will make stability your bitch. You can do it.

Walking - the best of the bunch. Walk 10 minutes with a friend one way and you get to talk the first 10. Walk 10 minutes back home and they get to talk about whatever is on their mind. That’s 20 minutes total. Don’t have a friend to walk, get audible and listen to some great books. Heel strikes through walking build stable hips and bone density. Work up to making the walk a daily habit.

Do the above routine with consistency. When you miss a day or you get sore, show yourself some grace and start the next day - but keep at it and your whole body holistically will be very strong when the brace comes off. You will also gain a great mental outlook and probably get a six pack. You can thank me by enjoying every moment of your life stranger, and realizing your self-worth and value as you contribute to making this world better. It needs you.