Grid gap is provided also for the first and the last item in a row. How do you override that?
Not really sure what do you mean.
For default usage, it doesn't apply the gap to start of the first item and end of the last item, which will be like

If you want to add some space for that, just add some margin to carousel item
here is the example:
https://63nui.csb.app/
https://codesandbox.io/s/quirky-forest-63nui?file=/src/App.js
I think this one might refer to the 20px margin on the far left and far right on one of the containers. I ran into that myself but have just offset it with a containerStyle on the main container:
<Carousel cols={4} rows={2} containerStyle={{margin: '0 -20px'}}>
Great component @x3388638 works well thank you!
your comment saved me @bazw