How can I enter recovery mode on my Mac mini running macOS Monterey?

You may also need a Wired USB Keyboard to get in.

Command (⌘)-R

Install the latest macOS that was installed on your Mac.

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

Shift-Option-⌘-R

Install the macOS that came with your Mac, or the closest version still available.

please see Intro to macOS Recovery - Apple Support.

Did you try booting with the Command + R keys held down  - Intel Macs or  (How to Boot an M1 Mac into Recovery Mode) 

NOTE: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.