  The objective of this paper is to discuss anisotropic solutions representing
static spherical self-gravitating systems in $f(R)$ theory. We employ the
extended gravitational decoupling approach and transform temporal as well as
radial metric potentials which decomposes the system of non-linear field
equations into two arrays: one set corresponding to seed source and the other
one involves additional source terms. The domain of the isotropic solution is
extended in the background of $f(R)$ Starobinsky model by employing the metric
potentials of Krori-Barua spacetime. We determine two anisotropic solutions by
employing some physical constraints on the extra source. The values of unknown
constants are computed by matching the interior and exterior spacetimes. We
inspect the physical viability, equilibrium and stability of the obtained
solutions corresponding to the star Her X-I. It is observed that one of the two
extensions satisfies all the necessary physical requirements for particular
values of the decoupling parameter.
