Here is a pattern for a plain sweater, and a sweater with a hood and pocket, which I have made for my grandson. As I could not quite find what I was looking for I decided to write my own pattern.
This pattern does not describe different sizes as it has been created as a made to fit a 2 – 3 month old baby.
A way to change your size would be if you used thinner wool and knitting needles, or thicker wool and needles, to create a larger jumper. Or, simply add a number of stitches to the body, sleeves and hood, and increase the number of cm (inches) to the current pattern, and there you go; you will have yourself a larger sweater.
I must point out that my knitting is quite firm, so depending on your own way of knitting, the final product might vary in size as to my specific measurements.

Yarn: Drops Lima 65 % Wool, 35 % Alpaca.
10x10 (4x4) = 21 stsx28 rows.
50 grams (1.76 oz) = 90 m (98yrds)

Usage for Plain Sweater: 3 skeins.
Usage for Hooded Sweater with pocket: 4 skeins.

Note: the pictures of the jumper / hoodie are showing white stripes, however this feature is not included in the description of the pattern. I will leave that bit to your own imagination!

Needles: 4.5 mm / US 7 circular needle 40 cm / 16” diameter (x 2). Body and sleeves are knitted in the round bottom up.

Size: 2-4 months (or a baby of 4-6 kilos / 8-13 lb).
Body width; measured flat across: 24 cm / 9”4
Full length incl neck: 26 cm/ 10”
Sleeves (from neck line down) 24 cm / 9”
Hood: 18 cm / 7”