As others have said no standing rooms tickets so just buy a seat and then stand. Dockers sell GA tickets but obviously the Eagles don’t. Just checked Ticketmaster and there are GA tickets available for the Rd 20 match Freo v Geel.
Yeah if you want to stand you just buy the cheapest ticket and park yourself behind a block on level 1. Security don't move you unless you're standing in a disabled bay or something like that.