  In this paper, we have obtained bounds for the box dimension of graph of
harmonic function on the Sierpi\'nski gasket. Also we get upper and lower
bounds for the box dimension of graph of functions that belongs to
$\text{dom}(\mathcal{E}),$ that is, all finite energy functionals on the
Sierpi\'nski gasket. Further, we show the existence of fractal functions in the
function space $\text{dom}(\mathcal{E})$ with the help of fractal interpolation
functions. Moreover, we provide bounds for the box dimension of some functions
that belong to the family of continuous functions and arise as fractal
interpolation functions.
