If I install TWRP on ramdisk, what is the button combination to boot into TWRP?

If we install our TWRP in ramdisk, which button combination do we need to boot again into the TWRP? In Xiaomi Poco M4 Pro 4G, there is no recovery partition, but there is a recovery software which we can access with the default button combination. I don't know in which partition the default recovery is stored.