Thinking about the Wonder Woman sequel and it doesn’t make much sense to me to skip over a good 60 years and go straight to the 1980s without at least explaining a few things along the way. It also seems bizarre to me that the character would still be in the “real” world throughout the 20th century without ending conflicts like World War 2, or at least significantly diminishing their horrors.
I’d go with Diana travelling the world for a few years after the end of the war but then finding her way home to Themyscira just before the Great Depression sets in and the world marches onto another massive war. She finds that her mother has passed away and some power-hungry Amazon has taken over the island, maybe as President rather than Queen. Diana is upset of course but is willing to remain Ambassador to the outside world and not challenge for the leadership spot. Of course, the incumbent ruler is frightened by Diana’s presence and so winds up betraying and imprisoning her. Diana is stuck behind bars for several years and things go from bad to worse under the new leader, with the island turning into a fascist state readying itself to go to war with the outside world. Diana does eventually escape and some of the Amazons side with her as the genuine Queen, leading to civil war on Themyscira. Diana wins in the end, of course, banishes her opponent and restores peace to the island. She then goes to return to the outside world but then learns of the horrors of World War 2 and decides that humanity is not able to be saved from itself and so stays on Themyscira, sealing it off from the wider world for good.
This then leaves the third movie to have something coax her back into the outside world – maybe with the villain finding a way to tease to her that Steve is still alive, which of course turns out to be a trap, and then something convinces Diana to have another go at spreading peace throughout the world.