  We simulate the dissipative dynamics of a mesoscopic system of long-range
interacting particles which can be mapped into non-Hermitian spin models with a
$\mathcal{PT}$ symmetry. We find rich $\mathcal{PT}$-phase diagrams with
$\mathcal{PT}$-symmetric and $\mathcal{PT}$-broken phases. The dynamical
regimes can be further enriched by modulating tunable parameters of the system.
We outline how the $\mathcal{PT}$ symmetries of such systems may be probed by
studying their dynamics. We note that systems of Rydberg atoms and systems of
Rydberg ions with strong dipolar interactions are particularly well suited for
such studies. We show that for realistic parameters, long-range interactions
allow the emergence of new $\mathcal{PT}$-symmetric regions, generating new
$\mathcal{PT}$-phase transitions. In addition, such $\mathcal{PT}$-symmetry
phase transitions are found by changing the Rydberg atoms configurations. We
monitor the transitions by accessing the populations of the Rydberg states.
Their dynamics display oscillatory or exponential dependence in each phase.
