The most reliable way to fix this is by using the by ThirteenAG. 1. Download the Essential Fix
The gold standard for this issue is the GTA SA Widescreen Fix. It doesn't just unlock 1080p; it fixes the UI scaling so your map and health bar aren't stretched horizontally. gta-san-andreas-1080p-resolution-fix-file
Download the latest build from the Widescreen Fixes Pack website. The most reliable way to fix this is
Using the ThirteenAG Widescreen Fix corrects the aspect ratio and scales the interface perfectly to 16:9 or 21:9 monitors. It doesn't just unlock 1080p; it fixes the
Open the game, go to Options > Display Setup > Advanced , and you should now see 1920x1080 available in the resolution list. 3. Pro-Tips for the Best Experience
Drag the contents of the scripts folder and the dinput8.dll (the ASI loader) directly into your main game folder.