linux – Boot ubuntu on raspberry pi 4 with external ssd

i am trying to make a project where i use my raspbarry pi 4 as home server to test some school related things.
However the SD card read/write performance is to slow. Is there any way to boot from aan external ssd with a different os (ubuntu/ubuntu server) from te raspberry pi 4?
I have seen multiple ways on how to do this but it always ends up with copieng the sd card os (pi os) to the ssd. Is there anyone that can clarify this?

I am new on this platform hope this sums up my question good.
Happy to hear any tips or improvements!