Supersymmetry (SUSY) is one of the most interesting theories for Physics beyond the Standard Model and LHC experiments have searched for its evidence during Run1 and Run2. The search, on data collected during Run2, for direct production of top squark pairs in which each stop decays in two, three or four bodies (depending on the hypotheses assumed on its mass) was performed in final states with two opposite-sign leptons (electrons or muons), jets and missing transverse momentum. The search placed lower limits at 95% confidence level on the top squark and neutralino masses up to 1 TeV and 500 GeV, respectively. This contribution describes the discovery prospects of a top squark in events with two leptons in the final state in the High-Luminosity (HL) LHC phase, when the accelerator is expected to reach a center-of-mass energy of 14 TeV and an integrated luminosity up to 3000 fb$^{−1}$, reporting recent results from a Public Note by the ATLAS experiment.