Are you the admin?
This is not a “grid”, this is a masonry or tiles view of Topic List Previews.
There’s an option to force a horizontal view if the provided space is wide enough:
topic list tiles wide format
Demo site here: https://www.artofsm.art (minimise or dismiss the right sidebar using the provided buttons to see the effect)
btw, imho you could consider reducing those three columns to two as packing a total of 4 columns across the page (inc. sidebar) is visually quite busy? You could achieve that with some minor CSS modifications.
If you are not the admin, you can ask the admin about it.