Use a linear approximation for sin to find an approximation (this will not be linear) to the function sin(𝑥^3) near 𝑥=0 .

Not sure what you mean when you say "use linear approximation" to find an approximation which is "not linear."

At (0,0) the tangent line is y=0
Near x=0, sinx ≈ x - x^3/6

Maybe you can work with that.