The integration of various grid-enhancing technologies is crucial for addressing the current challenges faced in controlling transmission grids. The growing variability in energy supply necessitates innovative solutions such as advanced grid monitoring and control systems, energy storage technologies, and flexible grid infrastructure. These technologies are essential for balancing the intermittent nature of renewable energy sources (RESs) and ensuring a stable and reliable electricity supply. This paper offers a comprehensive review of grid-enhancing technologies, incorporating insights from worldwide academic papers and various existing industrial projects that address current challenges and enhance the functionality, reliability, and sustainability of transmission grids. The findings highlight that modernizing grid infrastructure and integrating cutting-edge digital technologies are vital for effectively incorporating a growing number of RESs and enhancing overall grid resilience and efficiency. In addition, the paper explores future opportunities for improving the control of transmission grids, emphasizing the need for continued innovation and investment to meet evolving energy demands and support the transition to a more sustainable energy system.