I’m currently loving folded hems on hats. Folks tend to either think folded hems are Hard & Scary & Fancy, or they shrug and say sure I can do that.
And I truly think which camp you fall into has more to do with how your brain is handling life at the moment than anything else (because sometimes anything new is Just Too Much right now, and I get it). But if you’ve not done them before, and you’re in a headspace where you don’t mind trying something new, they’re pretty chill.
Start by working a provisional cast on (doesn’t matter what kind, anything that will let you unzip it and get to the loops is fine, I literally google ‘provisional cast on’ every time I want to do it and try one). Then work until your fabric is about twice as tall as you want the folded bit to be.
Unzip the cast on and get the loops onto needles. It doesn’t matter what kind of needles (dpns, circs, slightly different size whatever, it’s fine) or the orientation (you can change it later). Just catch them.
Wrangle the cast on edge up to meet your live stitches, with the wrong sides of the fabric together. There’s no smooth way to do this. You’ll feel like you’re dancing with a handsy octopus. That means you’re doing it right. Work a row of stitches joining one stitch from the cast on edge and one stitch from the live edge. Again, the particulars aren’t super important. I generally do a right-leaning decrease combining one stitch from the cast on and one stitch from the live stitches. But you could do lots of slightly different things, and as long as you’re bringing those two edges together, it’ll be fine. I’m half way through that joining round here.
When you’re done, you have a lovely tube of fabric, with the knit side showing all around, and no clear start or end point. It’s warm and lovely and comfy. And pretty darn simple! Especially if you just focus on the concepts and don’t get too hung up on the details. Because there’s more than one right way to do this (and most other things in knitting). And if you understand what’s happening, you can pick a right way that works for you. And you don’t have to obsess over the particulars!