I struggled from this, now im healthy and good. If you get it bad it's not trivial to fix and takes time. I heard way too many advices on chin tucks which don't work, so this is my view points:

There are many causes of this to talk about, but the most crucial thing about this weak forward head postures is the lack of your understanding of thoracic extension. How often in modern age do we need to look straight up to all the way behind? This is exactly what thoracic extension does and we slowly forgot about its muscles group and function.

Neglected muscles become weak over time, but your head and neck are solid weights to balance on, a forward head posture is going to dip all of your head and neck forward and down, and bend, bc your weak thoracic spine cannot hold.

You keep forgetting thoracic extension, then your C1-3 crooked as a result of trying to bring the head closer to balance and keeping your sight forward. The problem is not up top on C1, but rather it is down beneath the throat. Btw, the crooked C1-3 is the real chin tucks, not of muscles, but of your spine. Good luck fixing that with chin tucks.

This is what you should do, thoracic extension, on standing position, put your palm right beneath the bottom of your throat, point your neck straight up to the sky from where your palm is(bottom of the throat), until the ears lie inline with the body, don't tuck the chin, hold that position for as long as you can, do it for reps and take rest when it need be. When you get stronger, put two palms at the back of the head to apply pressure, thereby adding load to this exercise. You will find that you struggle to look up, but it is okay all we need is to maintain the thoracic spine in good position and you should also feel that all the weight of head and neck are closer to balance during the exercise, no matter how crooked they are.

While performing thoracic extension, focus on the bottom of the neck(throat), don't tuck the chin. If you do so forcefully, the extensors are pulling your skull back and make your neck more bent. The proper way to couple chin tuck with thoracic extension, is that the extensors should pull the skull back along with a strong neck, to properly perform greater thoracic extension. The lack of strength is exactly the problem that's why they don't couple.

I guarantee you, you will see improvement in a week, if you follow that and train thoracic extension frequently. Good luck.