You’ll notice 4 display buttons at the bottom of the Block Library and the Fabric Library windows. These buttons allow you to change how many items you are viewing at a time. The buttons indicate how many columns will show at once in the library viewer.
Both the libraries allow you to display 4, 9, 16, or 25 items at a time. For items with more detail, like complex block designs, you may want to change the display to a smaller number so you can see a larger preview.
In the Block Library, you can choose to display the blocks as line drawings, in grayscale, or in color. To adjust the display of the blocks, click on the arrows. All the blocks in the viewer will change at once.