The Daughters of the American Revolution has a lot of free information on their site, https://www.dar.org/. If the veteran has descendants who are members you will see basic information on their service in the GRS, genealogical research, but the library also has digitized resources.
Hi Dan, Welcome to the one world WikiTree! Thanks for joining us!
I use the DAR and the SAR databases.
DAR Genealogical Research Database
SAR Patriot Database