I also do some simple back stretches, like trying to touch my toes, even if I can't quite reach them; and some simple exercises like sit-ups or crunches. These help strengthen and stabilize the back. You don't have to become an Olympic athlete, but even a little bit of these things can be a great help in reducing or eliminating back pain.
Things like dead bugs and reverse crunches maybe, but doing crunches and back
stretches is probably not a great idea. But if it helps, it helps.
OP, it really depends on your postural deficiencies. Low back pain
can be a result of a lot of things not even related to your back
. I have knee issues sometimes that largely disappear when I do self myofacial release on my calves, hamstrings and glutes.
If you really do want to have better posture, your best bet is to find a solid weight training program that includes a lot of upper back
strengthening (upper body pulling) and squats/deadlifts.