Quick answer: AnyAspectRatio is a free Decky Loader plugin that installs aspect-ratio fixes for over 100 games in one tap, defaulting to the Steam Deck's 16:10 1280x800 screen and also supporting ratios such as 4:3 and 3:2.
Black bars are a common sight on the Steam Deck, because many games are made for 16:9 screens while the Deck uses 16:10. A new free Decky Loader plugin called AnyAspectRatio aims to fix that with one tap per game. Its developer introduced it on Reddit, Notebookcheck reports.
The plugin scans every Steam library, including the microSD card, finds supported games you own, installs the matching aspect-ratio fix and sets the Steam launch options for you, with no Desktop Mode file copying or terminal. Non-Steam games are matched by their exe name, and resolution, aspect ratio and FOV can be changed from Game Mode. Fixes default to the Deck's 1280x800 resolution, and other ratios such as 4:3 and 3:2 are supported, so it could help on other devices that run Decky.
The compatibility list covers more than 100 games, including Clair Obscur: Expedition 33, Resident Evil Village and Dark Souls III. Many of the fixes come from modder Lyall and are included unchanged, and the developer says not all of them have been tested yet. Some fixes only work with specific game versions, and the developer says to use them on anti-cheat or online games at your own risk.
For now the plugin installs from a zip on the project's GitHub releases page, using Decky's developer mode. Version 1.3.0 adds an offline mode and a log viewer. Notebookcheck notes there's little user feedback so far and results may vary from game to game, and the developer calls it a side project that will be updated when time allows.
Tested on the channel: How to Make SteamOS Better on the Legion Go 2 with Decky Loader (video) · full article