Js video player wordpress modification full screen to 854X480 max on desktop... -- 2

Hi, I have a video player on my site. I would like that the video player could be watched in full screen on every device which resolution is less then 854X480. But when you click on full screen on a bigger device like laptop then there should be a pop up with a fix maximum 854X480 Size width. If you want you can also change player.

Please note I want mobile full screen indeed mobil full screen. I don't want the phone buttons to be able to see pls check attachment.

If you can't do full job just a part of it, I can not pay.