do LinkedIn posts matter

Posting more on LinkedIn will not make you a better hire or look like a better hire. Why would you even think so?

(Assuming we're not talkng about a position where a large part of your work consists of spamming social media)

If your company has fewer than 100 people, LinkedIn is a waste of time.

If your company has somewhere between 100 and 3000 or so people, LinkedIn might help both internally and as you network in whatever capacity you can.

Once you start dealing with companies with multiple thousands of employees, an internal networking tool should be available that will more directly impact your career if you spend your "LinkedIn effort & time" there instead

It matters if you want to get hired for a job in sales, marketing, or business development. Or if impressing people from those departments is important for your job. Otherwise it's not important at all.

LinkedIn would only matter if you had a good following and you were aiming for a role where having an audience would be beneficial.

I find LinkedIn and people who post excessively on LinkedIn insufferable so that might be a factor in the hiring calculus.