There are quite a few Houzz threads on this, and I am sorry I am not at my main computer right now where I could find the ones I have bookmarked. You can search for "hardware pull dimensions" or variations thereof. The general rule is that the pull should be one-third the size of the drawer width unless you are doing 2 cup pulls. So yes, you should do different sizes if possible. The uppers need pulls large enough that you can easily fit your hand underneath. There would always be exceptions to these general guidelines, of course.

My pulls are about 5 1/2" long and I used the same on all cabinets. It looks choppy if one does not.

@back2work yes I searched endlessly -I prefaced with that-and none really answered my question about uppers and lowers

5 1/2 is what we were thinking now

IMO pulls should be in proportion to the drawer size , you often also find if you go a bit larger you might have to install some horizontal and some vertical to avoid hitting cabinets. I find even 2 x5.5” pulls on a wide drawer not attractive not mention not convienient.This is agood example of both sizing and placement. Some of this depends on the style of pull also The ones in this picture are ones from Lee Valley and I use them very often on my kitchen designs but I do contemporary design. The Lee Valley ones come i s ahuge choice of sizes .