Sorry if this is a really basic question, but is it possible to separate the body and attach it to different nodes? I see in the device details website (https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html#v-nmos-fet) that there is a DNW for the pwell to be isolated, but it says that is optional. How do I specify this? When I use the 4 terminal symbol in xschem to generate the spice file, I can separate the body nodes, but when I regenerate the spice file in magic, the body nodes seem to always be tied to together? Is there an extra step I need to do in magic?

You need to use deep nwell. It is used to isolate two pwell bulks from each other. Take a loot at:https://github.com/armleo/armleo_gpio/blob/main/gds/user_analog_project_wrapper.gds.gz It contains a armleo_gpio module which has two power domains with dnwell. You can use it as reference. Pay attention to nwell and dnwell.

@User thanks so much for the clarification!