Settings

Portfolio → Settings (or Grid Layouts → Settings without the portfolio):

Tab	Options
Portfolio	Turn the portfolio on or off; the project, category and tag addresses.
Breakpoints	Screen widths where grids switch to their tablet and mobile settings. Defaults: tablet up to 1024 px, mobile up to 767 px. Match them to your theme.
Image Sizes	Widths of the images WordPress makes for grids: Small 500, Medium 800, Large 1280, Extra Large 1920 px (heights follow each image). New widths apply to new uploads; regenerate thumbnails for existing images.
Lightbox	Enable the lightbox; use it for WordPress Gallery and Image blocks linked to the media file too; show captions (the image caption or the item title).

With the lightbox off, layouts set to Lightbox open the image file instead.