Detached garage subpanels have specific code requirements that differ from interior subpanels. The big one that people get wrong: in a detached building, the subpanel needs its own grounding electrode system (ground rod at the garage) AND the neutral and ground must be separated at the subpanel, with the ground tied to the local ground rod, and only the EGC feeding back through the feeder conduit (no neutral-to-ground bond at the sub).
For the feeder: four wires minimum - two hots, neutral, and EGC. You can use aluminum for the feeder (much cheaper on long runs). For a 60A feeder to a garage, that’s 4 AWG aluminum or 6 AWG copper for the hots and neutral. The EGC can be smaller per Table 250.122 - 10 AWG copper for a 60A OCPD. Use schedule 80 PVC underground (minimum 18" cover) or rigid (24" cover).
At the garage panel: separate neutral and ground bars. Ground bar connects to the local ground rod. Neutral bar is insulated from the enclosure. The feeder neutral lands on the neutral bar, the feeder EGC lands on the ground bar. This is the opposite of the main panel where neutral and ground are bonded. Get this backwards and you’ll have current on the enclosure.