How do I optimize for the singular version of a keyword where the plural version ranks better?

"Currently, the plural form of one of my important keywords is ranking #3 with an estimated search volume of 100. Conversely, the singular form of the same keyword, without the 's', is ranking at 18 with an estimated search volume of over 1k.

I want the singular keyword to rank higher, but in most cases, using the singular version doesn’t make sense (unless adding an unnecessary article).

Has anyone encountered a similar situation and how did you address it to improve the rankings?"

In some cases, Google may not differentiate between words with small variations like pluralizing or not.