Is it possible to add terrain deformation, I don't know but it would open many possibilities to tactics

Entrenchment tools could be add like in A2

Engineers could carry them by default and would have the ability to dig twice as fast as others

A series of holes can be dug to create trenches

Create your own H-barriers

The ability to cover up planted explosives

Blow your own foxhole with some C4 if you don't have an entrenchment tool

Make a trench on a well travelled road to slow vehicles and ambush them

I know the game has limitations and going below ground level is an iffy subject
but only a meter or so would be nice

The ability to climb would help tho even if its only up to anything that is chest height