This is how I made this scarf:
2 skeins super bulky yarn weight category 6, one large button, 25 mm hook, N hook
Double stranded, 25mm hook, chain about 150-200 chains. Enough to wrap in a circle 32” to 34” around (or diameter you want) 5 times (or as many as you want). I just laid mine out on the floor and wrapped in a circle the length I wanted, then wrapped around the circle 4 more times. On last time around you can add or subtract chains to make ends meet and join. I then crocheted a rectangle with an N hook and single strand of yarn. 3 rows of 11 hdc. Added a button, wrapped around scarf and button closed between the stitches. You can then pull on the loops to adjust.