Limited support
This feature is only present in Portal 2: Community Edition and Portal: Revolution.

cl_portal_crosshair_mode

🟥 Executable on Client only

cl_portal_crosshair_mode <value>

0: Portal 2 mode (Filled when portal is placed), 1: Portal 1 mode (Filled when portal is placeable)

Note:

The value is saved and will be restored on next startup.