The Current SharePoint Search Results Display of description cannot be modified.In results,Its picking up any random line from the document
In search results description,search is picking random line from the dcoument description instead of first line of the document.and we cannot modify this.This should be modifiable to make the search result more relevant.
Marjie Goodman commented
Page Description under Page Details is now editable. However, it doesn't seem to impact search results, let alone show up in search results as it says it will. This will empower content owners so much more if description has a heavier weighting in modern search.