I need to upload a TXT file to the root domain of a site. Is there a way to do that?
Not on Webflow, no. You can create a subdomain and host that file elsewhere at the root level. Something like
file.my-webflow-site.com if that helps.
Also check and see if redirect will work for your use case.
If so, you can upload the TXT file to assets, and then setup a redirect that points to it.