  Higgs boson properties are studied in the four-lepton decay channel (where
lepton = $e$, $\mu$) using 139 fb$^{-1}$ of proton-proton collision data
recorded at $\sqrt{s}$ = 13 TeV by the ATLAS experiment at the Large Hadron
Collider. The inclusive cross-section times branching ratio for $H\to ZZ^*$
decay is measured to be $1.34 \pm 0.12$ pb for a Higgs boson with absolute
rapidity below 2.5, in good agreement with the Standard Model prediction of
$1.33 \pm 0.08$ pb. Cross-sections times branching ratio are measured for the
main Higgs boson production modes in several exclusive phase-space regions. The
measurements are interpreted in terms of coupling modifiers and of the tensor
structure of Higgs boson interactions using an effective field theory approach.
Exclusion limits are set on the CP-even and CP-odd `beyond the Standard Model'
couplings of the Higgs boson to vector bosons, gluons and top quarks.
