Hi Charlie,
This is more of a feature request.
Currently it is not possible to use CSS Grid as a masonry layout (it was proposed 2-3 years ago and firefox added it as a beta functionality). It is possible to use JS to fudge masonry on top of CSS Grid ( ie macy.js or masonry.pkgd.min.js )
Would would be delightful would be if there was some ‘in-house’ themeco solution that works well with css grid, and uses the css grid layout, as the options above tend to ignore/corrupt the css grid layout.
Much thanks
Scot
PS, I can give examples of solutions/problems if you are interested