Use radar.cloudflare.com for a dashboard of tools that includes several useful lookups. Try them all, but my go-to is the URL Scanner that gives a detailed report breaking down security and tech characteristics of a target you're studying.

Worldwide Insights | Cloudflare Radar

Up to date global Internet trends and insights.

Use www.ssllabs.com/ssltest/ to check the TLS characteristics of your web server, and get actionable advice for improvements.