I know, it’s called legs up the wall pose, and I know what you’re thinking: she’s not at a wall! I break the rules now and then, but it’s only because I’m a fan of fitting the yoga to the person and not making the person conform to the yoga. No yoga police here!
When you do this pose away from the wall, it’s somewhat of a core strengthener, whereas at the wall it is more restorative. You might also see versions of this with the back of the hips being supported by a block or bolster. Those are great options to ease lower back discomfort or if your hamstrings are too tight to keep the legs at a 90-degree angle. You might also try a version with the hands supporting raised hips (if your wrists feel okay in bearing the weight) and then it becomes a nice prelude to shoulderstand and/or plow pose.
Tip: flex the feet and push the heels up toward the sky. This increases the hamstring stretch, so use a bolster or block if needed. If you are away from the wall, engage the thigh muscles to stabilize and activate the legs and core. Don’t forget to relax the face - you only need to put effort in the lower part of the body.