where is the sim card on Revvl5G?

This link should help. It's on the left side.

https://www.t-mobile.com/support/tutorials/device/t-mobile/revvl-5g/topic/battery-memory-amp-storage/insert-sim-card/1

usually on the right side of the device needing a push pin to get it to open.

unless it was set up with a esim..