This app was mentioned in 10 comments, with an average of 1.40 upvotes
https://play.google.com/store/apps/details?id=com.shirobakama.wpchanger I have been using SB wallpaper changer for quite a while. Its a bit dated and has not been updated for a long time but works just fine. There are a few nice features like setting different pictures based on screen orientation and changing images by unlock rotation or a timer.
Try SB Wallpaper Change it fixed both the zooming and the darkened wallpaper issues:
https://play.google.com/store/apps/details?id=com.shirobakama.wpchanger
The only downside is the app's interface and that it lacks some features other than that it gets the job done.
Although I really wish I could enjoy recently used wallpapers tab in xiaomi's wallpaper changer app someday.
Had to use an app called SB Wallpaper Changer from the Play Store and in the settings make sure Fix image (no scroll) was checked.
I tried looking back but couldn't find it... And I have done a factory reset and this method doesn't work anymore. It worked if you upgrade to MIUI 12 from MIUI 11 without fresh reset.
For 12.5.1+ installing SB Wallpaper Changer App is the only temporary fix for now. Good news is MIUI developers already take notice and reported this problem so maybe fixed in future officially.
You can use https://play.google.com/store/apps/details?id=com.shirobakama.wpchanger to change wallpaper easily if you can't choose 1 or easily bored. I am using it for my Oneplus One and it works wonderfully.
Did you try this one? SB wallpaper Changer
I was using Image 2 wallpaper to resize/fit my wallpaper according to screen size. It might help you
Edit: While searching I found Casualis. I installed it to check app and It has most of features that you need. You can choose your own wallpapers by clicking on "My wallpapers" n "My wallpaper". Add your own wallpapers. Go to settings > Sources. Disable all sources except "my wallpapers". From general tab you can enable fit to screen option and change time settings. You can also buy in app purchase for more features.
Also try Claro pro. You can use free version to experience the app. It has some more customisation options. But I would suggest you to go for paid version if you like it.
I've used SB Wallpaper Changer for this in the past. Simple and works pretty well.
I've been using SB Wallpaper Changer but it's not that great so I'm on the lookout for something else.
I use SB Wallpaper Changer (it offers several ways to change the backgrounds) with images that I've downloaded from Bing homepage or throughout the years.
I've also used Google Walpapers and Bing Wallpapers