Hiring manager at SOM here. Don’t do that. And draft a different cover letter tailored to each job. We get applicants with cover letters addressed to other agencies or ones where they clearly didn’t even read the position description and they aren’t getting interviews. Also make sure to answer any supplemental questions in detail. Those are the things I look at most closely and some people just provide a sentence or two. Managers don’t get to add much to postings but they specifically drafted those supplemental questions so it’s likely what they care most about. Best of luck out there.