First case: $X_n=(-1)^nU$ with $U$ symmetric, not deterministic. In continuous time, $X_t=\cos(t+2\pi V)$ with $V$ uniform on $(0,1)$.
Second case: $X_n=x_n$ with the sequence $(x_n)$ deterministic and not constant. In continuous time, $X_t=x_t$ with the function $x:t\mapsto x_t$ deterministic and not constant.