The projects in the design space are organized by default, under 4 sections - 'UI Drawings', 'Powerups', 'Design Files', and 'Design Embeds'.
The projects inside each section are sortable. Just drag and drop the project thumbnails in the order you wish. The ordering is saved for the design space and it will be the view whenever you come back to that design space.
The sections can also be sorted. For example, you can bring the 'Design Files' or the 'Pinned Powerups' to the top, if that is the priority inside your Design space. The sorting permissions are available for the co-editor and admin users of the design space.
To sort the sections, hover over the timeline at the left side connecting the section headings and you will be able to see an up and down arrow.