How are Point features written to CSV?

As two columns, lat and lon, alongside any of that feature’s other properties.

What about Polygon/LineString features - do they get flattened to lat/lon?

No - a non-Point geometry is written as WKT text in a wkt column instead, since it can’t be represented as one lat/lon pair.

Convert GeoJSON to a CSV spreadsheet with lat/lon columns, in your browser.

Input (GeoJSON)

Output (CSV)

name,lat,lon
City Hall,37.7749,-122.4194

Runs entirely in your browser - nothing is sent to a server.

How are Point features written to CSV?: As two columns, lat and lon, alongside any of that feature’s other properties.
What about Polygon/LineString features - do they get flattened to lat/lon?: No - a non-Point geometry is written as WKT text in a wkt column instead, since it can’t be represented as one lat/lon pair.