Top panel: Comparisons of charged particle $v_{\rm n}\{2\}$ integrated over the transverse momentum range $0.2< p_{\rm{T}} < 3.0$ GeV/$c$ from Xe--Xe and Pb--Pb collisions for finer centrality bins in central collisions. Statistical and systematic uncertainties are shown as lines and boxes, respectively. Bottom panel: Corresponding ratio of $v_{\rm n}\{2\}$(Xe--Xe/Pb--Pb) coefficients.