@kurobita do you want stranded colourwork in general or actual fair isle? If the first, you could start with mittens or a hat, like https://www.ravelry.com/patterns/library/starkin (you could start with just 2 colours)
@kurobita if you want to do fair isle, you could look at the Shetland Wool Week hats, they’re super fun! Hazel Tindall designed a couple of them and she has many more patterns for small projects.