I would select a simple peel & press wallpaper with some texture.

you could do a faux window sticker...

https://www.dezignwithaz.com/moutain-lake-faux-window-murals-p-14751.html

A fun print might help it feel more like “a room”. Just keep the background light. Do you have room for shelves over your desk? You can wallpaper that and the larger back wall.

Instead of wallpapering, I’d avoid the trouble and cost, just paint a great paint color and add colorful curtains to hide the clothes. Add a large piece of art on the far wall and unique lighting in ceiling. It will be a lively space and if landlord requires, slapping on white paint before you move is pretty easy. Also replace lighting to the original and take your light with you.

Please show a photo of each wall and the appearance from outside the closet door.

Will you need a good Zoom background?

Is there forced air ventilation or will you be adding a fan?

Are the clothes for everyday or out-of-season storage?

First, organize the clothing area so it is more useful and less unsightly.

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Here, the office is behind drapes, but clothing could be hidden in similar fashion.

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The word that jumps out at me is “RENTAL”. It must be temporary and easily returned to the original condition.