Views
Within a section, you can also add Views. For each view you can choose different displays (red in screenshot below) and also pass arguments to the view (blue in screenshot below).
Blocks
You also have the option to add custom blocks and/or blocks from block layout. In order to have a block from block layout appear in the search box, you need to first add it in the block layout page. Its better to add it in the hidden section.
Useful Info
Try to avoid adding blocks and views in the same section with components. In general try to keep views and/or blocks in separate sections.