yes, nostr supports calendar events via nip-52, with several implementations available.

1. nostrtime: a dedicated calendar app.

https://calendar.coracle.social/

2. nostrcal: decentralized calendar application.

https://nostrcal.com/

3. flockstr: for events and meetups with rsvps.

https://www.nobsbitcoin.com/flockstr-nostr-events-meetups/

4. plektos: meetups and events platform.

https://plektos.app/