How to display items smaller and 4 across the page

-- url of the page with the problem -- : agjewellery.uk/J4Test/index.php/jewellery-shop/earrings
-- HikaShop version -- : 4.7.2
-- Joomla version -- : 4.2.9
-- PHP version -- : 7.4.33
-- Browser(s) name and version -- : Firefox 102.9

I'm currently working on a Joomla4 upgraded site which rather than upgrade the current J3 site, I opted for starting from scratch & just building it up manually to speed things up (trying it the other way had too many errors).

So my main site has my items in a 4-column setting but I'm lost as to where or how I can change that in my new site where it's automatically set at 3-columns. I should perhaps say that I got Hikastart initially as part of a Quickstart template package where everything had been done, but I didn't use it for the new site, instead starting from scratch. And yes, I have read the documentation, but TBH got rather lost as there's just so much in it I was just overloaded & unsure what was relevant to what I was trying to achieve & also didn't want to muck up something that's working fine for the sake of a small change.

Also, I know this is more probably either a Joomla or browser setting, but is there a way to standardise the number of items normally shown on a page before it moves to Page 2 etc i.e. in one section there are 9, another section shows 20, while another shows 13?

Thanks.