There is no sugar-coating this. On a standard Switch, the game looks like a PlayStation 2 title upscaled to 4K. Textures pop in, mountains look like clay, and the framerate chugs in busy areas.
If you're looking for the Pokémon Scarlet version 3.0.1 update, the most reliable and safest way to obtain it is through the official Nintendo Switch update system. Version 3.0.1 was released on January 31, 2024 pokemon scarlet 301 nsp link