This paper investigates the evolution of spectrum sharing models, including their regulatory frameworks. Spectrum sharing is not a new concept. Over the past decades, models and regulatory frameworks for spectrum sharing in cellular networks have undergone immense development. With the recent advancement in wireless communication technologies, bandwidth demand has accelerated rapidly, making the electromagnetic spectrum scarcer. There is great motivation from governments and regulators for the efficient assignment of the fifth-generation frequency bands to alleviate the spectrum scarcity issue. The database-assisted spectrum sharing models associated with TV White Spaces, Licensed Shared Access and Spectrum Access System can be used to optimize 5G spectrum sharing. Spectrum sharing can be either cooperative or non-cooperative. Effective spectrum sharing models will reduce the costs of owning licensed spectrum and enhance the consumption of underutilized spectrum resources to increase efficiency. We can predict that radio spectrum sharing will be a foremost significant field for innovation, regulations, and standardization in coming years and beyond.