How can I shoot a 60fps video?
Disclaimer: Haven't tried out this proceedure since my device is not current supported.

Requirements:


Magisk (or TWRP)
MIUIcamerav2_whyred (magisk module)


Since you have a rooted device I'm assuming you have magisk installed already, if not then install it, as it will make the work easier.


Basically you need to download the module MIUI Camerav2 port (from Mi A2 series) and flash it in recovery/via magisk manager.



  Notes: For  MIUI based ROM, the packages are a simpler version
  because there is no need to install another camera, stock one is
  already MIUI Camera v2. The mod just enables more functions in the
  stock app (you can see from the function list what is enabled and
  what is stock). Depending on the MIUI version there are more function
  like
  60fps available. 


If camera don't start check permission, try to clear app data (it will reset permission too). 
If still not working wipe cache and dalwik from TWRP.