You can try, but success is short lived (and you may be, too)
The Tarrasque (MM, 286) is a:
monster of the Material Plane
Because of that, Banishment (Basic Rules, 217) can work, but you'll only have a minute until it comes back if you're fighting it on its home turf.
If the target is native to the plane of existence you're on, you banish the target to a harmless demiplane. While there, the target is incapacitated. The target remains there until the spell ends, at which point the target reappears in the space it left or in the nearest unoccupied space if that space is occupied.
Good chance it makes the save
But that's if it fails the save at all.
The Tarrasque has advantage on saves against magical effects, it has three uses of Legendary Resistance daily and can choose to make the save, and it's still got a +9 modifier to Charisma saves. Odds are it's making that save.