applications - How can I run apps in an isolated environment on my smartphone?

I have apps that I don't trust or that I just want to try. The problem is that even after deleting them they can leave files/spyware/malware/etc.

What are my options?

I have Xiaomi mi4c on MIUI with google apps but will soon format it and might replace the ROM.

Answer

Xiaomi MIUI has a feature called SecondSpace. It sets up a completely isolated 2nd instance of Android similar to a VM. You can have completely separate settings there and not affect your "real" phone.