I was in the same situation and found that wall decor is a total game-changer. You don’t need to drill holes or paint – just use removable hooks or adhesive strips. I bought a few art prints from
https://wallartpostersbylucid.co.uk/collections/wall-decor/r/bedroom-wall-art/ and it transformed the whole atmosphere. The colors and designs brought warmth and personality, and when I move out, I can take them with me.