Answer
Parent function : $f(x)=3^x$
Refer to the blue graph below.
Work Step by Step
Recall:
The graph of the function $y=f(x)+k$ involves a vertical shift ($k$ units upward when $k\gt 0$, $|k|$ units downward when $k\lt0$) of the parent function $f(x)$.
The given function's parent function is $f(x)=3^x$.
The given function can be written as $y=f(x) - 2$.
With $k=-2$, the graph of the given function involves a $2$-unit shift downward of the parent function $f(x)=3^x$.
Thus, to graph the given function, perform the following steps:
(1) Graph the parent function $f(x)=3^x$. (Refer to the black graph below.)
(2) Shift the graph of $f(x)=3^x$ two units downward. (Refer to the blue graph below.)