L13
Officially L5. Unofficially there’s always pressure to expand your scope and scale and continually grow.
+1, its L5.
I'd say that unofficially it is L5. Managers will expect the jump to L6 eventually, and you'll probably end up in Focus if you are at Amazon for 3-4 years and aren't showing some seniority. Officially, most managers will say L6. You can get around this by jumping to different teams or orgs, or by being in an org where SDE promotions are slow, like AGI.
L6
realistically L6. if you bust your butt in an expanding org with hot skills, L7 is possible if you are a phd doing applied science. then L8 is possibly and L10 is the absolute ceiling.
L5
Depends on the org but that is mostly true. Some are L6
bdbui$2's reply is the answer. HR will say L5 is terminal, but as with most things (like promotion criteria) this can be overridden by individual leaders. E.g. certain VPs see L5 as not terminal, just like some Directors like to review all L6 promotions as well as have 2 L7 feedback providers-- neither of which are an explicit HR requirement.