Some USPS branches still have fax machines, but not all. It depends on the location. I called ahead and found that only certain offices provide it, usually for about $2 per page. If you want a clear explanation, https://orngjce223.net/ has an article covering which post offices still offer faxing and how the service works today. That article helped me figure out that my nearest branch didn’t, so I used UPS instead. Definitely worth checking there first.