Control your PS4 from your PS5 with Remote Play.
How to Stream Gameplay from a PS4
PS5 Remote Play - How to set up and enable Remote Play, including in rest mode, on the PlayStation 5
How to connect PS5 controller to PS4 console
PS Remote Play
Don't Start Over: How to Transfer PS4 Games and Save Data to a PlayStation 5
PS Remote Play - Apps on Google Play
How to control your PS5 from the PS4 - Android Authority
How to control your PS4 from your PS5 - Android Authority
PS5 Remote Play app pops up on PS4