In ultra-relativistic heavy-ion collisions, one expects copious rates of $\gamma\gamma$ processes through the interaction of the large electromagnetic fields of the nuclei which can lead to light-by-light scattering via loop diagrams. This process was directly observed for the first time at the LHC by ATLAS. Final measurements of light-by-light scattering with the full Run 2 dataset with substantially reduced uncertainties are presented. This process provides a precise and unique opportunity to investigate extensions of the Standard Model such as axion-like particles.