How to check whether remoter server support TLS 1.3
I am pretty sure openssl (you need at least version 1.1.1) is able to do this.
openssl s_client -connect www.example.com:443 -tls1_3
See https://raymii.org/s/tutorials/OpenSSL_test_TLSv1.3_connection_with_s_client.html as well.
Openssl s_client -connect ip:port -tls1_3
It can help....