You mean anterior pelvic tilt, like your lower back is arched? You could have any number of issues that can’t easily be diagnosed in this format, but based on that alone you probably have tight hip flexors (psoas in particular) and quadratus lumborum. Stretch your hip flexors (half kneeling hip flexor stretch) and do myofascial release work on them (psoas in particular) and your QL. Don’t stretch your lower back, that can cause more problems.
This sounds like “crossed pelvis syndrome”, look it up.
I used to have these same issues to some degree, what I would recommend on top of what I said above is doing the McGill Big 3 regularly, like before each workout and on off days as well, plus glute bridges to warm up, like 5 sets of 5 second hold/squeeze. When it comes to lifting, an extended spine is better than a flexed spine but you should be aiming to stay neutral. It will take time to fix this, but it can be done.