I dislike shooter games where you have to physically duck for cover and get back up all the time, without using your hands. It's too uncomfortable to keep doing it over a long session. So if there's no button for that I don't even buy them...
Then when I finally purchased one (Guns’n’Stories: Bulletproof), I finally realized : If you don't need or are willing to sacrifice 360° body rotation (by using a thumbstick instead of your body to rotate), then you can just sit down instead of crouching down in those games.
Not only you can crouch your head lower by sitting, but that's even more comfortable then having to stand up through the whole game 🙂