Neutrinos present a number of unanswered questions and are a leading candidate for the potential
hiding place of other new physics phenomena. Various of these hidden signatures of new physics
can be explored with the KATRIN experiment. The principal objective of KATRIN is to quantify
the neutrino mass through precision spectroscopy of tritium β-decay. Recently, KATRIN has
improved the upper bound on the effective electron-neutrino mass to 0.45 eV at 90 % CL and
is continuing to take data until end of 2025. Further, beyond the neutrino mass investigations
involve the search for specific Lorentz invariance-violating parameters, that are only accessible via
interaction processes such as the β-decay. Improved limits of the respective parameters have been
obtained, solely based on the first measurement campaign. Additionally, the possible existence
of an eV-scale sterile neutrino is being probed. Its existence is today predominantly motivated
by the Gallium anomaly and KATRIN is engaged in investigating the associated parameter space.
Furthermore, the β-spectrum is being scrutinised for general neutrino interactions, thus enabling
a broad search for novel interactions. Here, we present first preliminary constraints based on the
second measurement campaign.