I have done two quilts with blocks that were each very different, and some were different sizes. I made a "frame" with a coordinating color to bring each block up to about an inch or more larger than the largest block. (So the largest block gets a frame, too.) Some smaller blocks got two frames. Each block has it's own frame color. Then I put them all together with white sashing.
My granddaughter said it looked like a quilt show, and it did. So the name of the quilt is "Quilt Show".