"He is getting off."
Translation:Er steigt aus.
So this literally says "He rises out", which would make sense for getting out of a car, but would "Er steigt aus" also work for getting out of a large truck, or a bus? Where one's head and body might actually lower upon exiting the vehicle?
Yes, to get off a bus is aussteigen.
And to get off a horse is absteigen, "to rise down" if you want to analyse it literally!
So he's getting off say a bus or is he just "getting off'... Like um the type of getting off people do if they look at certain websites where people aren't wearing clothes and yada yada yada?
aussteigen is to leave a vehicle (car, train, boat, plane, etc.).
So, getting off a bus, for example.
yada yada yada is something like "bla bla bla" or "and so on / etc."
Would this also have the meaning of "setting off", as on a journey?
No, not at all.
First, aussteigen is a separable verb, so the prefix aus has to come at the end in the present tense.
Second, steigen does not change the vowel in the present tense so it is er steigt aus, not er stiegt aus.
I'm still figuring out how separable verbs work in German, but it's always nice when they are the same in English. "He gets off", not "He off gets".