Hi Edmond.
Yes, you can fix it yourself. This posture is a VERY common problem.
Lots of good youtube videos on how to correct it.
How to fix Anterior Pelvic Tilt
How to fix Lordosis
Also, it’s frequently seen along with Forward Head Posture
Along with what @Iceman44 said…
You need to retrain your brain to “know” what standing up straight feels like. As you look at yourself in a mirror from the side, you’ll feel like you’re tucking your tailbone - just to get neutral. Practice this until it begins to feel natural. It will take a few months, and you may always need to be aware.
Constantly correct it so you’re stacking your spine.
NOTE: The OHP tends to make people who have some anterior pelvic tilt want to stick their butt out to balance the BB overhead. No bueno.
Also, be REALLY aware of tightening your core/ abs are active and tight when you Squat and DL so you’re not putting your lumbar spine in a bad position.
Strengthen your opposing muscles - Abdominals.
There are MANY good videos for how to rehab this, but this is a nice one specifically for lifters. Alan Thrall’s channel is a favorite.
Best of luck!
Puff