The raising elephants SysRq sequence is useful, but nowadays it is typically not enabled by default. It’s pretty easy to set up though:
EDIT:
It is the same as the PrtSc key. Traditionally the keycap would say both SysRq and PrtSc, but a lot of manufacturers leave off SysRq because it is meaningless to most people.
On some laptops you have to engage the Fn key as well to get the SysRq/PrtSc key.