I kind of am doing this myself with a timeline where earth sound retrograde, or the sun rises in the west and sets in the east. Results in different local climates, global sea levels and greenery distribution, fauna evolving and even different sized ice caps and a large cyaenobacteria increase (which may increase oxygen levels). For the most part, ‘west coasts’ become cooler and wetter than otl whereas ‘east coasts’ become hotter and drier, though exceptions exist either way.
Worldbuilding civilisations and history has been pretty hard, I’ll admit, especially if you resist the temptation to plagiarise RL.