The NFL has plenty of policies consistent across NFL stadiums, but one that is not the same everywhere is a policy on bringing in signs for games. In the NFC West, for example, the San Francisco 49ers (Levi’s Stadium) and Los Angeles Rams (LA Coliseum) have a strict no sign policy. The Rams will allow them in with prior management approval, but otherwise it’s no signs. The Seattle Seahawks (CenturyLink Field) and Arizona Cardinals (University of Phoenix Stadium) do allow signs, although they have some restrictions on size and whether or not they obstruct views.
I bring this up because Levi’s Stadium has had some issues recently with an inconsistent approach to enforcing their no sign policy.