Information about the upcoming version appeared on the ResetEra forum. Its author is known in the community under the nickname Naftra, and this person has previously leaked truthful data about Sony releases before their official announcement.
At the time of writing, not much is known about the Extended Edition. Nafta announced that new story content would appear in the game. Therefore, you should not wait for a free update from the current version of the game to its extended version. The PC version is not reported.