The proposal aims to study the theory and phenomenology of models with VLFs, including Standard Model extensions and Two Higgs doublet Models. The focus is on precision gauge coupling unification, which are finite in number and lack complete global analysis. The dark matter aspects of these models have not been fully explored. The study will use current techniques, train human resources, and build new computational tools. The goal is to explore the dark matter aspects of these models and improve the understanding of physics beyond Standard Models.