This one is a bit tricky. For the most part yes, the game, and some NCPs will hint at how to evolve certain Pokemon in the game. For example, in Hammerlocke, there will be a "mission" of some sort where a NPC will ask you for an Applin to give to a girl. After a few dialogues, you'll get the Applin back, and the boy will give you an item (Tart Apple for Sword, and Sweet Apple for Shield.) In the text it says that it'll make a certain Pokemon evolve if you give it to it (Applin to Flapple if you have Sword or Applin to Appltun if you have Shield.) Same goes for Milcrey evolving into Alcremie (Spin while holding a Strawberry Sweet which you first receive in a shop in Motorstroke.) Other evolutions are rather obvious such as in Ice Stone to evolve Mr. Mime into Mr. Rime, or purchasing a cracked teapot to evolve Sinistea into Polteageist.
Overall I say you should look up how to evolve if you have any questions. It's better to know then just leveling up Pokemon hoping that they evolve
