Gstreamer video 4k

I the last past weeks I was trying to use gstreamer to play a 4k mp4 video h264 on console (without desktop) on my RockPi 4.
I was able to play the video in full screen, but I need to crop and display a portion of video in the specific position.
For example: crop the video from 100,100 to 200,200 and display it at bottom right corner of my screen.
Is it possible using the hardware acceleration?
I tested some gst-launch string on my laptop with Ubuntu, but the same string doesn’t work on RockPi, for example:
gst-launch-1.0 uridecodebin uri=file:///root/output.mp4 ! videoconvert ! videobox autocrop=false top=800 left=800 ! videoscale add-borders=false ! video/x-raw,width=500,height=500 ! kmssink
I see there is a gstreamer plugin “rgaconvert” but it doesn’t work, I think becaus rga driver is not installed.
Someone can help me how to setup my RockPi to accomplish what I need?