Sites like HDWallpapers and Mob.org provide categorized galleries where you can select the 1366x768 resolution directly before downloading.
Here are the best sources for these specific characters and resolutions: Download 1366x768 Arknights, Hoshiguma, Horn, G...
For dual-character art, AlphaCoders offers high-resolution downloads that can be cropped or scaled to 1366x768. Sites like HDWallpapers and Mob
You can find various 1366x768 options on HDQWalls and Peakpx , which feature her in different skins and action poses. Download 1366x768 Arknights, Hoshiguma, Horn, G...