You can put bigger tires and wheels on your truck without a lift kit but only if there's enough clearance in the fenders and wheel wells for the tires to turn properly and spin without rubbing the vehicles fenders or wheel wells.
So if the wheels will fit properly and the tires will not rub anything on the vehicle then a lift kit is not required to add the bigger wheels and tires to your truck.
I have a truck that has some bigger wheels and tires on the back and it's been fine except I have to watch my speed because my speedometer reads around 10 miles off what it really is traveling at.
My fuel mileage is not that great either but I don't drive the truck with the bigger tires and wheels as often as I drive my other truck or car.
If you want to add bigger tires and wheels to your truck that won't normally fit then you'll need a lift kit which will also help improve the ground clearance of the truck.