  We investigate thermalization dynamics of a driven dipolar many-body quantum
system through the stability of discrete time crystalline order. Using periodic
driving of electronic spin impurities in diamond, we realize different types of
interactions between spins and demonstrate experimentally that the interplay of
disorder, driving and interactions leads to several qualitatively distinct
regimes of thermalization. For short driving periods, the observed dynamics are
well described by an effective Hamiltonian which sensitively depends on
interaction details. For long driving periods, the system becomes susceptible
to energy exchange with the driving field and eventually enters a universal
thermalizing regime, where the dynamics can be described by interaction-induced
dephasing of individual spins. Our analysis reveals important differences
between thermalization of long-range Ising and other dipolar spin models.
