A motivating discussion is definitely worth comment.
There's no doubt that that you should write more about this issue, it may not be a taboo matter but typically people do not discuss these
subjects. To the next! Many thanks!!
Welcome to PickPlugins.
Sorry for my late response. You can use the percentage value under the Grid item width.
First, go to the Edit mode of your Grid.
Screenshot: https://i.imgur.com/TixSa4A.png
Then under the Grid settings, set a percentage value instead of a number.
Screenshot: https://i.imgur.com/hRJOFN9.png
Or, you can easily create a grid with our post grid block.
Go to a new page, and choose our post grid block from the block inserter.
Screenshot:
https://i.imgur.com/1ccNOIB.png
https://i.imgur.com/SscprRa.png
Let us know if it helps.
Regards.