Made with Gazzal Baby Wool Fingering (14 wpi) yarn, this classic boatneck sweater can be made in any adult size according to your measurements.
Pattern written out of my gauge and has lots of photos, video links to YouTube on difficult points of work, diagram, recommendations for taking measurements, as well as detailed calculations according to your individual measurements in centimeters and inches.

Pattern is written for a one-color jumper.

Materials: winter/summer yarn for your choice, measuring tape, needle for sewing parts, crochet hooks of the appropriate size for your chosen yarn.

Yarn examples for a winter jumper (use 3.5-4 mm hook size):
Gazzal Baby Wool Fingering (14 wpi), 191 yds (175 m), 50 g (1.76 oz), 40% Lana Merino, 40% Polyacryl, and 20% Cashmere Type Polyamide.
14:23

Yarn examples for a summer top (use 1.75-2 mm hook size):
Vita Coco Thread, size 10, 262 yds (240 m), 50 g (1.76 oz), 100% cotton, plied.

Skills level intermediate.

You should know the basic stitches: chain, single crochet (Double crochet for UK), Double crochet (Treble crochet for UK) and slip stitches.