>>115073 (OP)
tldr it's not a simple endeavor and one way or another you will have to do your own research at some point
Honestly it's such a specialized skill that it's very unlikely to run into someone who has practical experience with handmade plushies outside of a place where sewers congregate like their subreddit or something.
I have a relative with decades of seamstress experience and she still at times gawks in awe at how high the quality/price ratio is for plushies, not because it is incomprehensible how each part is made, but how competent is all looks for how cheap the product is. Underpaid labor and mass production will do that.
Making anything that complex means you have to make blueprints, iterate measuring, cutting, fitting, adjusting again and again. You don't have to start from scratch and there's certainly tons of blueprints available online (much like in the day those Burda magazines used to have patterns for hot pants and whatnot enclosed) that get you halfway there but you still need to understand how to read them, how to make them and how to adjust them so that it looks like a kobold and not Kermit the Frog or whatever ends up being the closest match.
If you're willing to commit to making multiple plushies then the bad news is that you probably can't cut corners and freehand raggedy-dolls with nothing but a needle&thread and your old cargo shorts, but the good news is that some shapes and parts are certainly interchangeable and when you already can make an Averi plushie developing a Nigveri won't take as long.
Equipment-wise, there's lots of old sewing machines left over from grannies being sold for peanuts on craigslist because the grandkids don't know a single thing about them. Some of these sewing machines have all the necessities. But you need to be mentally prepared that you will also have to troubleshoot and maintain them. Those fancy stitches use two spools that interweave just right and there is a good deal of precision required from the machine
Whatever you set out to do (if you do), the first things worth keeping that you will produce will probably be napkins, pincushions, pillows. Much like with most trades and artistic hobbies there is no shortcut to success, it's a journey.
Finally, any man, especially a bachelor, should have at least some experience with the needle, to enact basic field repairs on his clothing if necessary.