  A measurement is presented of a ratio observable that provides a measure of
the azimuthal correlations among jets with large transverse momentum
$p_\mathrm{T}$. This observable is measured in multijet events over the range
of $p_\mathrm{T}$ = 360-3170 GeV based on data collected by the CMS experiment
in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding
to an integrated luminosity of 134 fb$^{-1}$. The results are compared with
predictions from Monte Carlo parton-shower event generator simulations, as well
as with fixed-order perturbative quantum chromodynamics (pQCD) predictions at
next-to-leading-order (NLO) accuracy obtained with different parton
distribution functions (PDFs) and corrected for nonperturbative and electroweak
effects. Data and theory agree within uncertainties. From the comparison of the
measured observable with the pQCD prediction obtained with the NNPDF3.1 NLO
PDFs, the strong coupling at the Z boson mass scale is
$\alpha_\mathrm{S}(m_\mathrm{Z})$ = 0.1177 $\pm$ 0.0013 (exp)
$_{-0.0073}^{+0.0116}$ (theo) = 0.1177$_{-0.0074}^{+0.0117}$, where the total
uncertainty is dominated by the scale dependence of the fixed-order
predictions. A test of the running of $\alpha_\mathrm{S}(m_\mathrm{Z})$ in the
TeV region shows no deviation from the expected NLO pQCD behaviour.
