Answer
No.
See explanation below.
Work Step by Step
The main reason for applying the rule of substitution is to obtain an integral of less complexity, which would be easier to solve than the initial integral.
The substitution $\left[\begin{array}{l}
u=x\\
du=dx
\end{array}\right] $does not change the structure of the integral.
It replaces the variable name from $x$ to $u$, but nothing else changes. The new integral has exactly the same complexity as the initial one.
For example, consider:
$\displaystyle \int\frac{e^{3x}}{1+2e^{3x}}dx=\qquad \left[\begin{array}{l}
u=x\\
du=dx
\end{array}\right]\qquad =\int\frac{e^{3u}}{1+2e^{3u}}du$
Note that nothing except the variable name has changed.
