You can easily have HTTPS and XMPPS (both c2s and s2s) all on port 443:
https://wiki.xmpp.org/web/Tech_pages/XEP-0368#nginx
Anyway, it is a good idea to have fallback ports: 5222 for STARTTLS c2s, 5269 for STARTTLS s2s.
And don't forget the DNS entries:
https://wiki.xmpp.org/web/Tech_pages/XEP-0368#DNS_setup
And the host-meta/host-meta.json files:
https://xmpp.org/extensions/xep-0156.html