i saw this video and wanted to try it out myself but I can't figure out how he managed to change the gravity when going through a portal? he typed out a command at 1:18 but it doesn't work on my side, the whole command goes red.

I'm using version 1.18.1

After installing gravity changer, you will see a command stick to enable gravity change to a portal.

when i download it. i have the gravity changer items (like the arrows), but i dont have the stick?