Since after the upgrade of miui 9 into miui 10 I faced a problem to make persist.camera.HAL3.enabled=1
it didn't work out this time as it used to in earlier roms, after researching numerious post and threads I found out this is either a error or it missed out feature for the camera2api function.
Various post claim various methods bt nothing could work successfully as this one. If you know about magisk tool this would be a great module to do the work for you.
Especially the module I am posting here is for RED mi 4a (Rolex) go visit this git repo and download the module and flash from twrp or you can do it from magisk manager app. There you go with successfull camera2api enabled.
p.s: This module works systemlessly so you ain't need to manually enable whatsoever. You can mail me if you need for other devices too I can do the search and check the authenticity of work so you can enjoy what you've been looking for. _x_