  Differential cross-section measurements of $Z\gamma$ production in
association with hadronic jets are presented, using the full 139 fb$^{-1}$
dataset of $\sqrt{s}=13$ TeV proton-proton collisions collected by the ATLAS
detector during Run 2 of the LHC. Distributions are measured using events in
which the $Z$ boson decays leptonically and the photon is usually radiated from
an initial-state quark. Measurements are made in both one and two observables,
including those sensitive to the hard scattering in the event and others which
probe additional soft and collinear radiation. Different Standard Model
predictions, from both parton-shower Monte Carlo simulation and fixed-order QCD
calculations, are compared with the measurements. In general, good agreement is
observed between data and predictions from MATRIX and MiNNLO$_\text{PS}$, as
well as next-to-leading-order predictions from MadGraph5_aMC@NLO and Sherpa.
