I don't think you're using the term noir correctly. What Eberron has is film noir--it's set in the equivalent of the 30s, after all. No other setting actually does that.
If there was a “things people get wrong about Eberron” thread, this would be my number 1 item.
Yes, there are post-WW1 elements, but they’re more 1920s than 1930s.
But the Cold War aspect is more post-WW2. What happened to Cyre on the Day of Mourning was the magical equivalent of nuclear annihilation, and now everyone’s paranoid about it happening again.
The Last War, which was an on-and-off war of succession that lasted for a century, also takes a lot of inspiration from Europe’s various lengthy medieval wars and dynastic squabbles, particularly the Hundred Years’ Wars and England’s War of the Roses. Lots of shifting alliances, territory changing hands over generations, and so on.
Pre-war Galifar was kind of like the UK with a mix of the Habsburgs. Very 1500s onwards. (Yes, WW1 was the ultimate unraveling of the complex and fragile web of alliances the Habsburgs had created over centuries.)
Yes, there are trains and airships and magical street lamps. But magewrights are more like pre-industrial artisans than factory workers. They’re blacksmiths and carpenters with cantrips. More magical renaissance than magical industrial era.
Sharn looks kind of like NYC with its skyscrapers, but those towers are medieval castle towers made of stone, not concrete or steel. They’re impossibly tall because magic!
Post-war Breland is in a pre-American Revolution era, with its on-the-nose Swords of Liberty agitating to overthrow the king. Very 1700s.
The dragonmarked houses are a weird mix of corporate monopolies, Mafia syndicates, and aristocratic houses.
So Eberron is really a mishmash of various time periods and genres.
Yes, the 1920s are a major influence, especially since that’s when a lot of the pulp adventures from which Eberron draws inspiration were written, but it’s still wrong to say “Eberron = 1920s D&D”.