I'll play the weeb card for this one. I like danbooru, which mainly categorizes fan art for anime and such, and is the gold standard in community image indexing and categorization. Their main site is NSFW, but you can access an SFW version via safebooru. Here's an example of a search which yields some wallpapers:<p><a href="https://safebooru.donmai.us/posts?tags=ratio%3A16%3A9+scenery" rel="nofollow">https://safebooru.donmai.us/posts?tags=ratio%3A16%3A9+scener...</a><p>The images are available in their original quality, and they have detailed tags. You can search by aspect ratio, width and height, and details of the image - "colorful", "scenery", "cityscape", and so on, or by the artist, copyright, or featured characters. You can search up to two terms for free, or pay a one-time fee of $20 for 6 terms, and $40 for twelve.<p>The search features are documented here:<p><a href="https://safebooru.donmai.us/wiki_pages/help%3Acheatsheet" rel="nofollow">https://safebooru.donmai.us/wiki_pages/help%3Acheatsheet</a>