Abstract: Atom-like defects in solids are promising building blocks for quantum technologies, combining the controllability of isolated quantum systems with the versatility of a solid-state platform. Among these, group-IV color centers in diamond are especially attractive because their inversion symmetry supports excellent optical coherence, while their electronic and spin properties remain highly tunable through the local solid-state environment. In this talk, I will discuss two directions in which these defects can be harnessed as new kinds of quantum sensors. First, I will show that a resonantly driven germanium-vacancy center can function as an atomic optical antenna, generating a strongly enhanced local optical field that enables the sensing and control of nearby charge defects. Second, I will describe ongoing work showing that large strain can reshape the spin-orbital structure of group-IV centers, partially release the electron spin from its usual locking to the defect axis and allow its quantization axis to be modified by an external magnetic field, which provides a route to accessing and detecting a broader set of surrounding nuclear spins. Together, these results illustrate how group-IV color centers can be developed into novel quantum sensors in diamond from both optical and spin perspectives.