While I understand the downvotes, I think there is a reliable and factual way to answer it.
Not always at all.
Of course, each dictatorial regime has its specifities, and analysing them could easily explain whether it will always want more or not:
An agressive dictatorial regime is not (only) based on corruption, cruelty or willingness to be mean. It is based on ideology.
Few easy examples:
- Nazi Germany: Racial ideology
- Fascist Italy: Social ideology
- USSR: Social ideology
- Today's Russia (because I suppose that's why you're asking the question): Cultural ideology (?)
Understanding the ideology behind the regime gives you the key to analyze what the regime wants, and what people under regime could feel legitimate to want.
For example with Nazi Germany: Giving Tchecoslovaquia at Munich was not enough because regime and people mostly feel legitimate to "group Germans in Germany" as their theory said. But this is only the traditionnal pangermanism part of Nazi ideology. It was clear that Nazi Germany had a supplementary doctrine: Lebensraum, which meant conquering non-german territories (Poland, Russia). In theory, giving Russia and Poland (but it was not practically possible becaue France and UK could not decide for USSR) could have settled down Hitler's ambitions.
Today's Russia could be analyzed as such (as well as any dictatorial regimes, but also democracies): The ideology behind Russia's ambitions seems* to be cultural: recreate the Russian Empire with people of Russian culture (language, etc...).
If you agree with this vision, is Donbass part of Russia? Yes
Is Ukraine part of Russia? Not really but one could argue Ukraine and Russia were united from the Middle Age until 1990
Is Switzerland part of Russia? No, never.
So with this analysis (WARNING: might be erroneous of course is the underlying ideology is wrong), Russia might want DOnbass, Ukraine, and stop there and never try to conquer Switzerland.
*Alway difficult to speak of present
Of course not wanting to conquer someone does not mean you won't be at war with them. For example, Nazi Germany did not want to conquer UK but the war started because UK wanted to defend Poland.