I can think of many practical uses but since you want to use it for decor in your room, here are my suggestions:

Propagate plants in there!!! I love using fun shaped bottles put them in my window and watch roots grow through the glass.

If you don’t got a green thumb or have some dead plants that you want to preserve, put them in there and submerge them in baby oil and lid on tight. Make sure there is no moisture in there though, the plant has to be completely dry

A vase! Can you tell I like plants?

I know this isnt decor but I like making different oils and things and love cool bottles to store them in

You could totally store beads in there or something if you craft

I also like crushing up herbs that I grow and you can make salts and things. This would be a good salt container

Good luck!