OK. The simple answer is, in principle, why not? However, the size differential between the smallest and the biggest Kaiju is a factor of one hundred. Enough to cause a sharp intake of breath.
Societies by themselves aren't simple things. They are complex and multi-factorial. Complex and multi-factorial systems can accommodate a lot of variability. For example, the Kaiju might organize themselves geographically in groupings by size. This could add a whole new meaning to the commonplace phrase "the big end of town".
Also, different Kaiju might different in other ways too. Some might fly, others breath out radioactive fire, tunnel at high speed through ground, live underwater or inside volcanoes. Again this would result in different clades of Kaiju living in different places and climes.
One part of this question, it is only possible speculate about and that is what the environment is like in this alternative dimension. With right sort of environment or even environments, all kinds of Kaiju be accommodated in places suitable for them.
Societies arise when people and presumably sapient Kaiju, have a need to cooperate, to work and live together in reasonable harmony. Usually this means by living together in orderly and cooperative arrangements this advantageous to the members of the society. The advantages can economic or ecological. Living together leads to a better quality and standard of life. It enhances their survival and safety. It provides protection from predators and enemies.
Quite likely, like humans there will be a multiplicity of Kaiju societies, social and cultural institutions, and political organizations. The equivalent of our nation states. Farms producing foodstuffs. Manufacturing industries too. Even forms of entertainment, with possibly professional and amateur performers and artists.
In principle, Kaiju societies could be just as practical and beneficial as human societies. Certain factors such as the environment(s) in which they exist will also need to be considered.