combine photos on mac finder

https://www.makeuseof.com/combine-photos-into-collage-macos/

6 Quick Ways to Combine Photos Into a Collage on macOS

Select all the photos to combine > right click > open with preview.app > 

select one photo > select all and copy(A) > tool > adjust size > unlink lock icon (scale proportionally) > enlarge with or height > drag all(select all) and delete > paste(A) >

select the picture from the sidebar and select the whole canvas and copy > go back to the first enlarged canvas and paste