Ironically, the next time I am in the market for jeans, I will be specifically avoiding Levis due to their inconsistent sizing. I have owned probably 15 pairs of the same cut in the same size, but some are too big and some are too small. I can never know until they get here (brick and mortar stores never have my size, so I must order online).
I've never had that happen, within the same type. I had some loose-fit Levis 568 which were very different, but the 501s never change. Just switched from 40w to 38w, got exactly the size change I expected.
My complaint is an extremely common one. I have seen plenty of people complain about it here on lemmy and on reddit as well. Perhaps 501s are more consistent, since they are the flagship (IIRC), but that's not the cut that I prefer.
I have had this issue as recently as one year ago. Half of the ones I ordered fit perfectly, half I couldn't even button. All the same size. I went online to find many people with the same complaint, and even videos of how they manufacture their jeans and why it happens. It was the last straw for me. I got fed up with sending my jeans back every time.
I usually wear Levi's 511 but they've been going down in quality over the last 10 years. Newer pairs didn't last nearly as long as old pairs. Sizing is inconsistent now too. I'm looking for a better brand in the same style...