Wallpapers

Hi all, I've been searching the web for a long while now and I can't find anything. Maybe it's just my rusty English (second language of course). I have an app called "dynamic wallpapers" that creates two wallpapers into one where one is light and the other is dark. The light one is automatically selected by my system when I have the light theme on, and the dark one is also automatically selected when I have the dark theme on (I hope this makes sense). I use the gnome desktop on Linux if that helps. So, I'm looking for wallpapers that are exactly the same, but one is dimmer than the other for both themes. For example, a picture of a mountain with the sun above it, and another with the same mountain and everything, but it's night time and the moon is there instead of the sun. Or just like the windows 11 default wallpaper, the light one and dark one. I really hope I'm making sense. Please ask me for more details if I'm not making sense. Does anyone know of any website that has such wallpapers? Please let me know. I'd very much appreciate any help. Thank you.