It is pretty unanimously agreed by linguists that all language is equally expressive, which makes sense considering they were all made by humans to do the same thing.
Language is a product of Geography and Culture to express a "Philosophical Worldview". Mere study of its Phonology, Morphology, Syntax and Grammar are not enough. What is important is whether a given language has specialized technical vocabulary to express specific concepts/ideas i.e. the "complexity of semantics" involved. These are usually context/culture dependent.
As an example, compare the language of the Xhosa people living in equatorial Africa with that of the Chukchi people living in the Arctic Circle. It should be obvious that they each have concepts expressed via language unique to their Geography/Culture and which are unknown to the other.
As another example, consider the Sanskrit word Karma (https://en.wikipedia.org/wiki/Karma). It is impossible to understand this word in all its connotations (it actually is a stand-in for a whole lot of concepts) without having an idea of Reincarnation which is specific to Hinduism/Buddhism philosophical worldviews.
I have studied Linguistics from the pov of Philosophy which any intelligent person should be able to infer from my references.
I don't think you even understand what the phrase "All languages are equally expressive" means. It means very different things when applied to Natural Languages vs. Formal Languages. The latter is where this expression is usually used/studied which is what you are parroting without any understanding.
For your edification, i highly recommend reading about the well-studied Pirahã language - https://en.wikipedia.org/wiki/Pirah%C3%A3_language Note in particular the reference papers/books by Daniel Everett on the Pirahã - https://en.wikipedia.org/wiki/Daniel_Everett