Question: how to evolve eevee to sylveon in sword and shield?
Answer: Once you think you have Eevee's friendship level high enough, the key to getting Umbreon is to level Eevee up during the night time. Doing so in the day time will evolve it in Espeon. To obtain Sylveon, you will need your Eevee to learn a fairy-type move (Eevee learns the move Baby-Doll Eyes early on).