Apple runs a fleet of stratum 1 NTP servers at time.apple.com. In my experience, ntpd/chronyd are very happy with them.
It looks like, instead of doing anycast, they maybe use DNS to steer you to the closest one.
time.apple.com is a CNAME for time-osx.g.aaplimg.com. Querying a handful of DNS servers, I've identified the following locations:
| IP | Hostname | Location |
|---|---|---|
| 17.253.2.125 | usdal4-ntp-001.aaplimg.com. | Dallas |