The mod improves the 16:10 experience by removing the black bars (or the dimming and distortion, depending on what you're trying). It should be helpful if you play on the Steam Deck.

1. Unpack the archive to the mods folder within the main game folder.
2. Launch the game and enable the mod by checking its box
3. Quit the game
4. Open %USERPROFILE%\AppData\LocalLow\Nolla_Games_Noita\save_shared\config.xml in a text editor and change internal_size_h="720" to internal_size_h="800"
5. Launch the game again - the mod should be working now!