How to degrade the Google search application in recovery?

For some reason, I would like to degrade the Google search application (com.google.android.quicksearchbox) to an earlier version and update later, in an MI 8 with Android Oreo.
But when / system is mounted in recovery, I could not find the Google application in / system / app, although there are other applications of the system.
I do not want to root the device, then, how?