Yeah they do? It’s how governments and groups try to legitimize their occupation and claims. It’s how the USSR operated in Eastern Europe with Russification.
That does not make it acceptable to kill the civilians. Russian citizens in Crimea are not enemy combatants. They can be evicted if they won’t peacefully integrate with the rightful owning country, but they shouldn’t be raped or killed.
Note that this is very different from the Israeli settlers. They exist in a grey area because they are committing violence against the Palestinians there and generally being awful shitheads and active colonizers.