To validate or convert XML files into text, HTML or PDF formats, you can use the IETF Author Tools available at https://author-tools.ietf.org/.
Alternatively, the xml2rfc tool can be used for similar conversions. Install it using pip and run following commands to generate an HTML file:
# pip install xml2rfc
# xml2rfc ./draft-lxin-quic-socket-apis.xml --html
You can also view the latest submitted version on the IETF Datatracker: