(top) Normalized transverse momentum correlator, $\sqrt{ \langle\langle \Delta p_{\rm T1}\Delta p_{\rm T2} \rangle\rangle }/{\langle \langle p_{\rm T} \rangle\rangle }$, shown as a function of the charged-particle multiplicity density, $\langle{\rm d}N_{\rm ch}/{\rm d}\eta \rangle$, in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ and 5.02 TeV; (bottom) Ratio of values of $\sqrt{ \langle \langle \Delta p_{\rm T1}\Delta p_{\rm T2} \rangle\rangle }/{\langle \langle p_{\rm T} \rangle\rangle }$ measured at $\sqrt{s_{\rm NN}} = 5.02$ TeV to the corresponding results at $\sqrt{s_{\rm NN}} = 2.76$ TeV. The statistical and systematic uncertainties for both energies are represented by vertical bars and boxes, respectively.