I got my just turned 3 yr old a Parker tee. This is the spruce green size 2/4 on my 36” 30lb 3 yr old(50th percentile so she’s almost exactly average for her age).
Sleeves go down to her elbow, shoulder fits exactly to the edge of her shoulders. Hem hits right at crotch level. It fits well now but there’s room to grow too.
She loves it! And I’m excited to make some pinafores to coordinate!