  This study presents a universal relation for anisotropic neutron stars,
called the $I-f-C$ relation, which accounts for the local anisotropic pressure
using the Quasi-Local (QL) Model proposed by Horvat et al. \cite{QL_Model} to
describe the anisotropy inside the neutron star. This study analyzes
approximately 60 unified tabulated EoS-ensembles, spanning from relativistic to
non-relativistic mean-field models, that comply with multimessenger constraints
and cover a broad range of stiffness. The results indicate that the
relationship between the parameters becomes more robust with positive
anisotropy, while it weakens with negative anisotropy. With the help of the
GW170817 \& GW190814 tidal deformability limit, a theoretical limit for the
canonical $f$-mode frequency for both isotropic and anisotropic stars is
established. For isotropic case the canonical $f$-mode frequency for event
GW170817 \& GW190814 is $f_{1.4} = 2.605^{+0.487} _ {-0.459}\ \mathrm{kHz}$ and
$ f_{1.4} = 2.093^{+0.150} _ {-0.125} \ \mathrm{kHz}$ respectively. These
established relationships have the potential to serve as a reliable tool to
limit the equation of state of nuclear matter when measurements of relevant
observables are obtained.
