If the carpet is coloured, it can be an interesting starting point for the rest of the room: combine it with a cushion or a curtain or an armchair in one of its colours, and you're done!
I use rugs in all rooms: living room, dining room, bedroom, bathroom, kitchen, hallway, office, etc. The trick is to adapt the material to the room: in a technical room like the kitchen or bathroom, choose a rug that is easy to wash regularly, without too long a pile. In a bedroom, you should choose a soft rug for the gentle touch under your feet.
In the living/dining room, it all depends on how you use these spaces, but think practicality in everyday life (comfort, cosiness, patterns, brightness...).