Originally, GTA Online took place in 2013, sometime before GTA 5's events.
However, that's no longer the case. Any event before the Gunrunning update in 2017 still takes place in 2013. Anything associated with Gunrunning took place in 2017. Every event afterwards takes place at the respective time of the update.
Hence, the Los Santos Tuners update's events take place in 2021. The chronology of GTA Online doesn't change how players play the game, and it's merely a part of the game's lore.
The timeline of GTA Online events spans a couple of years
Every GTA Online update up to and including Cunning Stunts takes place in 2013. It's not specified what the exact date for all of these activities is, except that it takes place before GTA 5's story.
For example, readers can take a look at Trevor Philip's involvement in GTA Online. In this case, it's before he reunites with Michael. Here, the player primarily helps Trevor steal drugs from the Lost MC and other rival gangs. The last time they saw Trevor in 2013 was during Series A Funding, where he evades the DOA.
GTA Online players still hear about Trevor Philips in the modern era, suggesting that he canonically survives the events of GTA 5.
That's just a small example of GTA Online's events primarily taking place in 2013.
GTA Online from the Gunrunning update onward
As some players might know, GTA Online no longer takes place in 2013. Instead, it takes place from 2017 and beyond. The exact year depends on when the update occurs.
The following is a rough estimate of 2017's events:
- Gunrunning
- Smuggler's Run
- The Doomsday Heist
Here is what happened in 2018 for GTA Online:
- Southern San Andreas Super Sport Series
- After Hours
- Arena War
2019's updates were:
- The Diamond Casino & Resort
- The Diamond Casino Heist
Likewise, 2020's events consist of:
- Los Santos Summer Special
- Cayo Perico Heist
Finally, 2021 only has the Los Santos Tuners update thus far.
What was the GTA Online protagonist doing between 2013 and 2017?
Some curious players might be wondering what the GTA Online protagonist was doing during GTA 5's story and afterward. Lester Crest hints at this by saying:
"I've been working with someone but they're too unpredictable."
The GTA Online protagonist is unpredictable, as everybody plays the game differently from one another. One can deduce that this character is probably doing something uneventful during this timeframe.
They could repeatedly be doing activities from 2013, but there is no confirmation on their actions from 2014 up to 2017.
The timeline doesn't affect the player's actions in-game
As previously mentioned, these dates are mostly mentioned to maintain lore consistency. GTA Online players can still participate in any activity from the 2013 updates (if they're not removed) in 2021.
However, it means any event in 2022 will canonically take place in 2022. It would continue for the upcoming years unless Rockstar Games changes it up as they did with the Gunrunning update.