I stumbled across a free Barbie heart Valentine's sweater pattern but my first attempt was clearly going to be too large for Barbie so I turned it into a tank top for Ken and then made him a pair of pants to make it a set. You can find the pattern here.
I haven't given up on this for Barbie I just need to find the right fiber. It suggested fingering weight yarn so I tried size 3 thread and a D hook which was suggested. This clearly was too big. I'd make this in the future for Ken as a fun Ken and Barbie set but I am considering if I want to join as with Barbie's bent arms it makes getting clothes on and off more challenging.
I did not use the white finishes for Ken as I went with a tank top rather than the Barbie sweater.
The pants are my standard go to of measuring and sewing a piece of elastic together waist size for the doll. I then single crochet around the elastic for the first row. The rest of the rows are in dc. When I reach the crotch I split with a chain 4 reducing I believe to 15 dc per leg.
