Your doll looks absolutely cute in this hat with cat ears.,
Cathat is knitted in round from bottom to top.

Size made: Doll with a Head Circumference: 33-34 cm
Needles: 2.5–3 mm needles for knitting in the round
Gauge rows in: 28–32 s/10 cm
Pattern for gauge: Blocked stockinette stitch
Yarn: You can use any Fingering yarn.
Yarn used in pattern’s hats: Filcolana - Arwetta Classic, 80 % superwash merinovilla, 20 % nailon
Colors used:
Deep red #139
Desert Rose #187
Light grey #954
Yardage: 50g/210m/230yrds
Skeins: One skein is enough for a hat.
Needles:
Use your preferred size US 1.5-2.5/2.5–3 mm needles for working in the round.
Notions:
Tapestry needle.
Gauge:
28–32 sts = 4”/10 cm in blocked stockinette stitch.