Yes, compensation of 0 EV is trying to properly expose the picture, meaning a goal of proper exposure level. This is true of both TTL flash exposure and of ambient exposure compensations.

The problem is that if TTL flash is used in bright ambient, the sum of those two proper exposures (the metered flash and ambient) are then 2x too much exposure (of the near subject illuminated by flash). So we necessarily back off, and know to use maybe -2 EV TTL flash compensation when in bright sunlight ... which sum is still a very minor low overexposure, but it can go unnoticed. My site has a calculator of this at https://www.scantips.com/lights/flashbasics4a.html#percent

Then the concept of Balanced flash was invented, when the camera automation tries to properly back off on the flash itself. That menu surely still says 0 EV flash compensation, but the flash (in bright sunlight) will actually be near this -2 EV level, if Balanced flash. Nothing says that, but it's how it works. That reduced flash level is the meaning of Balanced flash, which is often the default today.

However, then (Balanced flash), the flash compensation menu can still modify that somewhat, to be more or less flash. However, sometimes this balanced automation can have its own ideas and goals, and possibly override expected results a bit.