How do I choose Eevee's evolution?

I've been thinking about getting "Let's go Eevee", but I wanted to check that it's not too hard to choose Eevee's evolution. In Pokémon Go you had to use various nicknames to choose Eevee's evolution, but in other games I think you had to use a specific evolution stone.

If you have to use nicknames like you did in Pokémon Go, then are they the same and what nickname corresponds to which evolution?

If you have to use an evolution stone, then how do you get each evolution stone and how far in the game do you have to be to get them?

If neither of these are the correct way to choose your Eevee's evolution, then how is it done and how hard is it to do?

Solution 1:

Your starter in the Let's Go game can't evolve.
All the stones are sold in the department store in Celadon city for 5000.

Free stones:

• Fire stone- Pokemon Mansion on Cinnabar Island
• Water stone- Route 12
• Thunder stone- Power Plant

Solution 2:

If you mean the Eevee you get as a starter, it can't evolve at all.

Any other Eevee evolves by its usual method: Fire Stone for Flareon, Water Stone for Vaporeon, and Thunder Stone for Jolteon. All of the elemental evolution stones can be bought at the Celadon Department Store.