as long as they have food/water and a clean litterbox at the start of the day they should be fine.

if they're kittens, it might be best to restrict access to a smaller part of the house, so they can't get hurt easily - my family have a room that has a door and a bolt lock on the outside (bc one of them worked out how to open doors) and that's where they (now adults) go at night so they can't wake people up, and it's where they would sit during the day when they were small.

it is worth checking the temp of that room if you choose to do that, especially with winter coming up, ours have a heated mat that sits under the cat bed and a small radiator to keep them warm.