Do you know what kind of techniques you're looking to learn? There are the crochet plushies that people make called Amigurumi, and there are knitted ones as well. Then there are sewn plushies, which can be as simple or as complicated as you want. There are a ton of felt-based plushies that have patterns for sale on Etsy along with detailed instructions. Most people start with felt, I think, because it doesn't unravel and you don't have to worry about finishing the seams.
Here's a pattern I've used before that was really easy to follow and super cute:https://www.etsy.com/listing/226734160/flora-the-explorer-pdf-pattern
If you're looking at doing crochet, there's a website that lets you build your own pattern based on drag and drop pieces. Not sure how detailed the instructions are, but it's a cool tool once you're familiar with crochet patterns:https://make.amigurum.io/design
Ravelry.com also has a TON of patterns, both free and paid, and covers both crochet and knitting.