Investigating collectivity in proton-proton ($pp$) and proton-nucleus ($p+A$) collisions is essential for understanding the mechanism of formation of Quark Gluon Plasma (QGP). In $pp$ collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 13 TeV, ATLAS has reported no impact on flow coefficients when excluding low-$p_{\mathrm{T}}$ jets, indicating collectivity in small systems does not originate from hard processes. Comparing flow decorrelation in Xe+Xe and $pp$ collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.44 TeV and 5 TeV respectively, underscores the role of sub-nucleonic fluctuations in determining longitudinal energy deposition. ATLAS has also reported a significant correlation between event-wise flow and transverse momentum fluctuations in Xe+Xe and Pb+Pb collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.44 TeV and 5 TeV respectively, emphasizing the role of nuclear structure in accurately describing bulk observables in heavy-ion collisions and provides the first experimental evidence from a high-energy experiment for a significant triaxiality in $^{129}$Xe.