I mean Fortnite came out in the last 5 years... Doubt they saw that coming.

Aside from that and the already mentioned ones:

Monster Hunter: World - Even if they expected it to set a new franchise record, they defintely didn't see coming how it exploded in the West compared to previous entries. And since we're talking abot Capcom:

Resident Evil 7 - Another game that set a franchise record and which has had incredibly strong legs.

Horizon Zero Dawn - I'm sure they knew they had a hit on their hands, but reaching 20 mil for a new IP is super rare and they probably didn't see that coming.

It Takes Two - The critical reception and awards really did wonders for this game as it has already reached 5 mil, outperforming what their previous game did over years.

Hollow Knight & Cuphead - 2 HUGE indie debut games, released in the same year to boot.

Hades (probably) - Supergiant has had one crazy success before in Bastion, but the games they made in the meantime didn't reach quite the same heights, so I think they were probably pleasantly suprised when Hades once again reached peak Indie stardom.

Fortnite comes to mind. I remember seeing its first reveal. It received no hype and I'm sure many like myself were a bit dissapointed that we weren't looking at a new epic single player franchise like Gears of War, or a technical powerhouse to show off UE4.

I'd also say GOW, Spiderman and Horizon. Up until this point Sonys first parties would typically sell 2-7m outside of Naughty Dog. Even though Spiderman was a huge IP, I don't think many expected to be Sonys fastest selling game.

Monster Hunter World.

Super Bomberman R

Sonic Mania

Stardew Valley

Hollow Knight definitely surpassed Team Cherry expectations

Astral Chain and Sakuna of Rice and Ruin