How large-scale structures formed in the early universe is a key cosmological question with few answers from empirical evidence. Unveiling galaxy clusters and their high-z progenitors (i.e., protoclusters) is essential to picture galaxy evolution drawn by the hierarchical formation scenario. However, unveiling these early structures at high redshift (z > 1.5) in large astronomical surveys is still a challenge. In the context of the preparatory work for the Euclid mission, we are characterizing through simulations the best strategy to detect galaxy protoclusters in large photometric surveys. The characterization of these large-scale structures and the derived detection method are about to be tested in deep and wide multiwavelength surveys such as COSMOS and HSC-SSP, combined with the NIR ESO-SHARKS survey. Exploring the synergies between the upcoming Euclid's protocluster catalogue and the Large Radio Surveys is of great interest. Potentially, it could increase the purity of the candidate's sample, unveiling the formation of the Brightest Cluster Galaxy (BCG) at the core of the proto-structure and characterizing the hot intergalactic medium at these early cosmic epochs. In this contribution, I will present the results based on the Euclid-like simulations, purity and completeness to expect within the optical protoclusters catalogue and I will highlight the main challenges of the work.