Hi @venepress-web,
We do understand your requirement but that is Horizontal/Vertical Posts Widget It always has the maximum posts of 5 number, First with the bigger Thumbnail and rest with the smaller. If this widget have more than 5 posts then the design layout will be messed up. You can see the actual layout of same widget at the left main content which automatically fits in a grid way. The same widget on the side bar will be shown like you share in the image but if you see the same sidebar widget in tablet view then the layout will changes to its original layout and again changes at the mobile view. But if you really need more that 5 post then you need to hire a developer to customize the code for you.
Thanks