How to determine by what percent the target variable will change if we change a variable by some percent in Linear Regression? I trained a linear regression model on some data. Now I have the intercept and the other coefficients. How to relate that with percent change in target given some percent change in a feature, keeping all others constant?

Let's say we have fitted a model such as:
$$ y = x_1 + x_2 + \epsilon$$
and we obtained esimates giving the following equation:
$$ \hat{y} = 2x_1 + 3x_2 $$
Thus for a 1 unit change in $x_1$ we expect a change of 2 units of $y$.
It is not possible to get the expected % change in $y$ from a % change in $x$ unless the variables are on a log scale prior to running the model.
