Go to from the main menu. You should see a new save slot with a preview image (likely showing Jimmy wearing the Black Ninja outfit or completed story percentage). Load it.
To use a pre-completed save file, you must manually move it into the game's data folder using a file manager like FV File Explorer Save Location Android/data/com.rockstargames.bully/files bully anniversary edition 100 save game android
If you prefer the honest route but need help, here’s the fastest way to 100% without cheating: Go to from the main menu