Would your granddaughter perhaps like some doll’s clothes? If so I could point you at some very simple patterns.
I’ve also made dolls’ blankets for my Gdd when she was about the same age. From memory about 50 stitches using two strands of double knitting together on fat needles, maybe 5 or 6 mm.
I would knit 4 rows of garter stitch first (every row knit), followed by stocking stitch (knit one row, purl one row), but keeping the first and last 4 stitches of each row just garter stitch, and the very last 4 rows garter stitch too, to make a nice border.
If you would like to knit toys, I can recommend Jean Greenhowe’s pattern books - if you google you will find plenty. Virtually all her patterns are designed so that anyone with basic skills can tackle them. You just need to be able to cast on and off, knit, purl, and do simple increasing and decreasing. And unlike so many patterns, her instructions are crystal clear and meticulously detailed.