What kind of door? What kind of knob?

Latch sets have to be spaced correctly. Pull knobs can be anywhere, but in the half of the door on the opening side, rather than the hinge side, you'll get a better vector and won't have to pull so hard. There is an old tradition of a knob centered in a door, especially in double doors. It works, but it works better closer to the opening. Latch sets, of course, have to be right at the opening and at the correct spacing for the latch to operate correctly.

A standard location for knobs on shaker cabinet doors is where the diagonal from the inside corner of the edge pieces (on the opening side) to the outside corner, crossed by the same line at 180°:. In other words, in the center of the square formed by the corner of the rail and stile. People who use pulls, instead, often have one end of the pull in the same place as above. people who use extra long pulls often center them on the raised edge.

You can do knobs in the same kind of place for raised panels (since no one's doing the centered in the panel knobs anymore). For slab, you can do an "as if", that is, the same place it would be if there were a raised edge. A "standard" measure is 2 1/4".

In general, so long as you can open the door, you can put the knobs wherever they look good.

Once you've decided where they go, make a template so you can get them in the same place on every door.

Thank you, plllog - My husband wanted input from GW before we start drilling. The template is a great idea! Once the drill goes thru, we're stuck. The doors are solid slab, same with drawer fronts. It sure will show even if we're a little out of measure. With the drawers, the pulls I got have two holes instead of one; measuring will be crucial. I think your template idea will solve that problem. THANKS!

You're welcome! The template is what the cabinetmakers do. :) They make it out of scrap wood, with edges that fit around the edges of the door so that it fits right in. The hole is drilled at the right place in the template and then they just drill with the bit starting in the hole. Just make sure to drill really straight and level.

I fund some online guides https://www.knobdepot.com/pages/installation-guide, https://hickoryhardware.com/blogs/news/how-to-install-cabinet-knobs-and-pulls maybe they will help