How to enter Android recovery?

After executing adb reboot recovery, an Android robot appeared, but I don’t know how to enter it. I’ve entered it before by randomly pressing buttons, but I’m not sure how to press them.

(Translated from Google)

Are you are using the officially released version?
On our end, the Recovery menu displays normally during testing.
Could you please share the serial port logs? The method is as follows:

I flashed the user version, not the debug version. Flashing the debug version worked, but when I tried to flash Gapps, the recovery wouldn’t let me because it lacked an official signature.

(Translated from Google)

Would you like to replace it with a third-party Recovery?

I just want to flash GAPPS to use Google services. (Translated by Google)

I have synced your request with our R&D, and we will integrate this feature in a future release.
In addition, we plan to open-source our Android modification patches later this month, so you will also be able to implement the changes yourself as needed.