Is gta online part of the main gta v story?

The verified evidence describes Grand Theft Auto V as a single-player action-adventure game centered on three protagonists—Michael De Santa, Franklin Clinton, and Trevor Philips—and their heist-driven narrative within the fictional state of San Andreas. The text does not mention GTA Online, which is a separate multiplayer mode introduced post-release. Since the evidence focuses exclusively on the single-player story and lacks any reference to GTA Online's integration or narrative role, there is no basis to conclude it is part of the main storyline. The absence of information about GTA Online in the provided source means its relationship to the core narrative cannot be confirmed or denied based on this evidence alone.