The frame size is far more important than wheel size. I have 700c, 26 inch and 29 inch wheel size bikes. The frames are all different as well, because the frames are designed for different things.
Generally speaking larger wheels will give a longer wheelbase and more ground clearence. Neither wheel size fits a taller, longer inseam person better than a shorter person. I've known shorter riders to ride 29'ers, but with 16 inch frames.
Frame size determines whether a bike fits or not. It's possible to make an educated guess, but with ebikes, that could be an expensive mistake. If you don't know the best size bike, it's best to get a professional fitting and do test rides. Your local ebike shop may be able to do it, if not Google bike fitters near you. Everyone has access to a good bike fitter these days. I've seen fitters charge $60 and up. They generally have reviews online.