All u-blox GNSS receivers output position data in the WGS84 reference frame by default. This can be user-specified in the CFG-NAVSPG-USERDAT configuration.
Corrections and Reference Frames
When high-precision corrections are used, such as RTK or PPP, the position output follows the reference frame of the correction source:
PointPerfect Flex uses ITRF2020
PointPerfect Live uses a regional reference frame, depending on the country
u-blox receivers do not carry out internal transformations between datums or reference frames. The reference frame of the output is set by the correction data when corrections are used; if not, it defaults to WGS84 unless user-specified.
Handling Datum Differences
If your application requires positions in a different reference frame or epoch, you must apply the transformation externally.
Use geodetic libraries such as PROJ.org for precise, time-dependent transformations
For many practical uses, a simple local offset may be enough
Note: WGS84 and ITRF2020 are typically within 1 to 2 centimeters of each other worldwide. In some areas or with older WGS84 versions, the difference can be larger due to tectonic motion.