Top panel: Comparisons of charged particle $v_{\rm n}\{2\}$ integrated over the transverse momentum range $0.2< p_{\rm{T}} < 3.0$ GeV/$c$ as a function of centrality from Xe--Xe and Pb--Pb collisions. Middle panel: Ratio of $v_{\rm n}\{2\}$(Xe--Xe/Pb--Pb) coefficients. Bottom panel: Double ratio of data and theory. Hydrodynamical model predictions from EKRT and V-USPHYDRO are shown. In all cases, only statistical uncertainties are visible (thin vertical lines).