To factor $ x^{3}+3x^{2}+9x+27 $ we can use factoring by grouping:
Group $ \color{blue}{ x^{3} }$ with $ \color{blue}{ 3x^{2} }$ and $ \color{red}{ 9x }$ with $ \color{red}{ 27 }$ then factor each group.
$$ \begin{aligned} x^{3}+3x^{2}+9x+27 = ( \color{blue}{ x^{3}+3x^{2} } ) + ( \color{red}{ 9x+27 }) &= \\ &= \color{blue}{ x^{2}( x+3 )} + \color{red}{ 9( x+3 ) } = \\ &= (x^{2}+9)(x+3) \end{aligned} $$