  Quantum many-body systems undergoing phase transitions have been proposed as
probes enabling beyond-classical enhancement of sensing precision. However,
this enhancement is usually limited to a very narrow region around the critical
point. Here, we systematically develop a modular approach for introducing
multiple phase transitions in a many-body system. This naturally allows us to
enlarge the region of quantum-enhanced precision by encompassing the newly
created phase boundaries. Our approach is general and can be applied to both
symmetry-breaking and topological quantum sensors. In symmetry-breaking
sensors, we show that the newly created critical points inherit the original
universality class and a simple total magnetization measurement already
suffices to locate them. In topological sensors, our modular construction
creates multiple bands which leads to a rich phase diagram. In both cases,
Heisenberg scaling for Hamiltonian parameter estimation is achieved at all the
phase boundaries. This can be exploited to create a global sensor which
significantly outperforms a uniform probe.
