Not sure of the style. How old are they?

Adobe Illustrator is probably what they were made in if they are not super old.

Almost certain that they were made in some sort of graphic design software.

Art is subjective, however I think these can be categorised...

1. I would say is 'Pictogram' style.
e.g.

2. I would categorise as 'Retro-futurism' themed, in an almost Pictogram style.
e.g.

3. Is definately 'late' art-deco style. mid-to late 1930's. However I don't think it looks original (from 1930's), probably a modern rendition done in homage.
Just feels like it's missing some pale colour gradients and a bit of ... something... to be original Art deco.

e.g.

Here's a suggestion... computer graphics-y, done in an 'old' style..

Wanted this on my wall for a while above my sgi machines. 😀

I think you might find samples of posters in styles similar to No. 2 and 3 at Flashbak, if you do not mind browsing their archives of entries.

About those posters you're eyeing, the second one really seems to have a deep sense to it, huh? It's cool how art can do that, even when we're not sure what it's all about.If you're still on the hunt for similar styles or ideas, here's a suggestion. Have you thought about checking out Canvas Prints in Australia? You can find them at https://www.frameshop.com.au/canvas-prints. It might be a neat way to turn something you like into something a bit more special and unique. Canvas prints have a way of making artwork pop and feel more personal, you know?

Look up the space posters of Steve Thomas