In Settings for DuckDuckGo, throw the toggle for "Infinite scroll" to On.   It will present quite a few more results before the need to activate the "More Results" button occurs.

I cannot find anything that allows you to tell it to return, say, 50 or 100 results per page.  But when Infinite Scroll is on, while no longer literally infinite, you get quite a few more results on each page.

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Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363  

The purpose of education is not to validate ignorance but to overcome it.
       ~ Lawrence Krauss