Arrogate

Etymology

From Latin arrogare, "to claim for oneself," from ad- ("to") plus rogare, "to ask, propose." The sense of asking or proposing shifted into presumptuous claiming: to arrogate is to award yourself something as though no one’s permission were needed.

verb · /AIR-uh-gayt/
To claim or take something for oneself without any right to it.
What it names
The precise verb for seizing power, credit, or authority you were never granted — helping yourself to what isn’t yours to take.
Example
Over the years the committee quietly arrogated powers the charter had reserved for the full membership.
Related idea
Usurp is to seize a specific office or position by force; to arrogate is to help yourself to rights, credit, or authority more broadly.