  Results on collisions of $^{16}$O nuclei performed at the Relativistic Heavy
Ion Collider (RHIC) have been presented for the first time at Quark Matter 2023
by the STAR collaboration. $^{16}$O+$^{16}$O collisions are also expected to
take place in the near future at the Large Hadron Collider (LHC) at much higher
beam energies. We explore the potential of beam-energy-dependent studies for
this system to probe small-$x$ dynamics and QCD evolution. We perform 3+1D
IP-Glasma simulations to predict the rapidity dependence of the initial
geometry of light-ion collisions, focusing on $^{16}$O+$^{16}$O and
$^{20}$Ne+$^{20}$Ne collisions at $\sqrt{s_{\rm NN}} = 70$ GeV and 7 TeV. The
choice of $^{20}$Ne is motivated by its strongly elongated geometry, which may
respond differently to the effect of the high-energy evolution compared to the
more spherical $^{16}$O. We find that smearing induced by soft gluon production
at high energy causes mild variations in the initial-state eccentricities as a
function of the collision energy. These effects could be resolved in future
experiments and deserve further investigation.
