We consider a general interacting random walk loop soup that is related to several well-known statistical mechanics models, such as the Spin O(N) model, the double dimer model or the interacting Bose gas. We discuss the system in $\mathbb{Z}^d, d>2$, and present some recent results about the occurrence of macroscopic loops whose length is proportional to the volume of the system as the inverse temperature is large enough.