shelgon:

Although it was confirmed at E3 2018 that Shiny Pokémon were to be in Pokémon Let’s Go, Pikachu! & Let’s Go, Eevee!, we now have further information of Shiny Pokémon in these games through various Italian, French press reports as well as DotEsports in the UK. In the overworld, they will not appear in the shiny colours but will have a special shiny aura around them showcasing two stars. This is similar to the blue and red auras seen that denote size.

Source: Serebii