Thank you for attaching a screenshot; a picture is worth a thousand words - and with it we can better understand your question.
It isn’t possible to alter the proportions of the iPad screen layout.
Your iPad will display a 5x6 grid of App and folder icons. For iPadOS15, where Widgets are present on any Home Screen, the grid is reduced to a 4x6 grid with larger spacing to accommodate the larger Widgets. Each Widget occupies 1x1. 1x2 and 2x2 element of the grid, displacing App/Folder icons as necessary.
As noted in my earlier response, Apple do invite feedback and feature requests via the product feedback channel: