At the beginning of Pokémon Sword and Shield, you can't manage the game's audio options. Surprisingly, your only way to change the volume is to play directly with the Switch's volume. To be able to manage the game's volume, you will need to get a certain item after a few hours of play. Here's how it works.
Unlock sound options
Being able to customize the sound options is often something you can find in the default options of a game. This is not the case here.
To access these options, you will need an object: the Hi-Tech Earbuds.
This item will be given to you by an NPC from the city of Motostoke. It is located in the main aisle, near the elevator, in front of a store on the right.
Once you have this item in your possession, you will be able to access the sound options in the game settings.
You are now able to adjust the volume of the music and the sound, effects.
To get Mew in this version of Pokémon, you will need a specific item. It's unlikely that everyone is ready to step up to the challenge and get this famous mythical Pokémon.