You can try those dungeons minimum item level, which can make them a lot harder. You will probably beat them but they will sometimes make you think and involve deaths because the enemy damage is higher.

You can try doing 8-person extreme trials as an undersized party of 4. Some of them can still be challenging with only 4 people, so it can still be something that you overcome together.

You can also try POTD from floor 101, HoH and Rathalos as others pointed out.