To install Android 10 on a Samsung Galaxy S3, the most common method is through the LineageOS 17.1 custom ROM
The installation process is not for the faint of heart. It requires: samsung s3 custom rom android 10 link
The Samsung Galaxy S3 (GT-I9300), originally released in 2012 with Android 4.0.4, has seen an incredible extended life through the developer community To install Android 10 on a Samsung Galaxy