You asked
What accessories do I need for the sony rx10 iii?
The site doesn't have an accessory list for the Sony RX10 III, so I can't give you specific model recommendations for it. What I can tell you is that it has a built-in 8.8-220mm f/2.4-4 lens, so you won't be buying extra lenses for it. Its full page has the specs, including its 1-inch sensor and in-lens or in-body stabilisation.
If you plan to shoot video, the filmmaking section explains why ND filters matter. They let you keep a sensible shutter speed in bright daylight.
Written by Claude from this site's pages.