>>410772027
5 player co-op? Most I can think of are limited to 4. Pavlov has some good zombie modes but you already listed that. VTOL has >4 player custom PvE missions. You could play Zenith as a 5 man group and steamroll everything. VRChat has different co-operative worlds that support that many players but I'm not trans so I can recommend any. Vox Machinae technically counts if you fill all the other slots with bots.
Somewhere in the middle of PVE and PVP you've got Climbey.
Team based PvP other shooters like Contractors you can stack a team in the lobby. Hyperdash when it goes f2p should get enough players for you to play as a 5 man team.