Answer
False
Work Step by Step
Let us consider that the function $f$ is periodic function with period $T$ .
$f(t+T)=f(t)$
Now, $f(t+T)=\sin (t+T)^2=\sin (t^2+2 \pi)$
Also, $(t+T)^2=t^2 +2 \pi\\ t^2+2tT+T^2=t^2+2 \pi \\ 2tT+T^2 =2 \pi$
Therefore, the given statement is $\bf{False}$.