  We experimentally study the tunability of the cooperativity in coupled
spin--cavity systems by changing the magnetic state of the spin system via an
external control parameter. As model system, we use the skyrmion host material
Cu$_2$OSeO$_3$ coupled to a microwave cavity resonator. In the different
magnetic phases we measure a dispersive coupling between the resonator and the
magnon modes and model our results by using the input--output formalism. Our
results show a strong tunability of the normalized coupling rate by magnetic
field, allowing us to change the magnon--photon cooperativity from 1 to 60 at
the phase boundaries of the skyrmion lattice state.
