We're taking a look at how-to evolve Applin into Flapple or Appletun in Pokemon Sword and Shield! This isn't too difficult, but you will need to know some specific places to go to obtain the correct items required to get each specific evolution.
Where-to Catch Applin
Travel to the Pokemon Nursery at Route 5! If you go straight down from where you fast travel, you will find a few areas of grass where they can spawn. They can only be found via the exclamation point in the grass, and they are a somewhat rare spawn. So you might need to keep trying for a bit.
Catch it however you want! I'm personally a big fan of Quick Balls, but using a high level Pokemon with False Swipe is a great option as well. Be sure to place the Applin into your party!
How-to Evolve Applin into Flapple & Appletun
Fast travel to the left most Pokemon Center at Hammerlocke. Hop on your bike or run to the left until you encounter this guy:
He will ask you if you've heard a rumor. Tell him you haven't, and he will then ask you for an Applin. Give it to him! There will be some story dialogue, and he will inevitably end up giving you back the Applin. He will also give you either the Tart Apple (Sword) or the Sweet Apple (Shield) that we're looking to obtain! Go into your bag and under Other Items scroll to and find either of the apples. Give the item to Applin and it will evolve into Flapple (Sword) or Appletun (Shield)!
That's all you need to know to evolve your Applin into Flapple or Appletun!