Click on the Tablet breakpoint at the top of the viewer where you have the four device icons, to start with.
Then click on the CMS Collection Item that you have classed as dyn flex child home2
Now on the Style panel, open up the Flex Child section and change this:

To something that will hold fewer items horizontally so that the items may be larger. Try bumping up the Basis to something like 33
(to hold 3 items), or even 50
(to hold 2 items wide), like this:
(That’s set at 50).
Find out which is to your liking, then click the
landscape device breakpoint at the top of your viewer, and change the same setting on that one for each breakpoint.
Basis, in case it’s too confusing, is the percent of the total that each item will take up, as a starting point.
Hope this helps.