Out of curiosity, do you mean too big as in capacity, or too big as in fit? I'm very tall and I've struggled with packs that don't rest properly on my hips, but I don't know if this was inexperience, or if there's some secret hack to adjust them.
There was a EU based, tiny equipment manufacturer that actually produced backpacks for very tall people. I had some contacts in travel related business that could have brought it back on track. I asked if the owner is willing to let me buy into the business (I was interested in other niche products in his business) but he preferred to close it down.