Analysis work is presented as part of a search for Emerging Jet (EJ) signals within the ATLAS detector at the LHC. These EJs arise in models with a QCD-like dark sector, where dark pions are produced during proton-proton collisions. These dark pions then decay into SM particles with a mean decay length between 0.5mm and 300mm, causing a jet to emerge. The analysis uses Monte Carlo events simulated with a hidden-valley implementation of PYTHIA (version 8.230) scaled to the LHC Run2 period (2015-2018) with integrated luminosity of 139fb^-1 and centre-of-mass energy of 13TeV. It includes a comparison study between these EJs and QCD jets, and a trigger study to verify that it is efficient in the search region of interest. Finally, a sensitivity study to probe the theoretical cross-sections of the EJ models is presented, which utilizes a data-driven ABCD method for two model-independent planes and a machine-learning, model-dependent plane.