The Lotus top is a made to measure and size inclusive pattern. You will need any type of 4ply fingering weight cotton yarn and a 3.5mm crochet hook.
You can use a DK/sport weight cotton if you prefer, just please note that you would need to go up a hook size and you may not meet gauge.
I used roughly 180m of 4ply cotton for the size XS (uk 6).