What to run
Open Whois Lookup, SSL Expiry Checker, and DNS Lookup. Whois and the certificate check are from Cloudflare. Whois is RDAP: registrar, statuses, dates, and nameservers. DNS Lookup is DNS-over-HTTPS from the browser and does not follow CNAMEs.
How to read the result
RDAP expiry is the renewal deadline.
Certificate days-left is independent.
NS tells you who can still edit DNS if you renew.
What to open next
Run all three and write down the two dates. Do not assume they match.