Anime scenery wallpaper?
Something like this or...
this (colorful, messy room). Preferably in a 16:9 ratio.
https://4walled.cc/ is a good wallpaper source, anime or otherwise. You can set the desired ratio and search by keywords.
https://konachan.com/post?tags=scenic
Konachan is perfect for what you're looking for.
Also use tags like
sky
clouds
nobody
etc.