I wis thinking of an Idea to allow officer in lcpdfr to order a civilian to the ground hands on car, or wheel etc...

huh i like the idea i hope they do something like that

Highly unlikely considering to create a script like this there would have to be animations like this already in the game, which to my knowledge there are no such animations. Then again it would be possible to "order someone to the ground" if all the animation was to just crouch and cower, like some peds do when they hear gunshots. 

As said above, new animations had to be implemented, something that I doubt the devs want to tackle. There are, however, animations for lying on the ground and an animation for getting arrested over the hood. You can use them with the simple native trainer.

yea I would like to see that