LLMs are a special type of transformer model, however several recent models have been multimodal, allowing for a variety of input and output type. So the question is if a neural network can approximate reality, not LLMs.

Though really, all embedded models of reality are approximate by nature, and based on stochastic empirical data. The real tradeoff with probability-based neural networks is whether a rigid algorithmic approach or a more flexible, but stochastic, approach solves the problem at hand.