Shiny Pokémon in Sword and Shield are relatively hard to find. There are only a few options available to the player to increase their chances of catching one of the elusive creatures.
While chaining does exist in the game, finding a shiny from this method can be a difficult task in a short period of time. Luckily for shiny hunters, there is one far easier method, albeit time consuming, available when it comes to getting shiny Pokémon.
The method that seems to be the most reliable is the Masuda Method (MM) with egg breeding. In short, this method centers around breeding two Pokémon of the same type (or Ditto with the starters or other compatible species) or Pokémon from the same Egg Groups from different languages.
For example, if you breed an English Pikachu from the United Kingdom or the United States with a Pikachu of the opposite gender from other regions, the chances of the Pokemon hatching from that Egg being a Shiny drastically increase.
The average chances of getting a shiny Pokémon by any means is between 1 in 4000, but the Masuda Method drastically decreases those odds.
Similarly, if you have a Shiny Charm, which you get from completing the Pokédex, the odds can drop to anywhere between 1 in 600 to 1 in 1000. So while the item will still be a grind, it is definitely worth getting.