This is the most relevant entry I found related to your request:
“1. From the parts library on the left, drag in a portal with a ground symbol to your schematic as a secondary ground. (Search for it in the library!)
1. Ground portals behave identically to normal portals (discussed below) and differ solely in their visual appearance as a symbol in the schematic.
Once you’ve connected your ground portal component, connect the secondary ground to the primary through your desired filter/bypass capacitor or any other filter network, as necessary.
Ensure that all ground portals share the same name so they will then share the same secondary ground net in the PCB editor.”