The y-intercept occurs when $x = 0$. To find the y-intercept of $f(x) + 3$, we first calculate:

$f(0) = 10^0 = 1$

Then, we add 3:

$f(0) + 3 = 1 + 3 = 4$

Thus, the coordinates of the y-intercept are $(0, 4)$.

The ordered pair is:
$(0,4)$

Would you like any additional details or have further questions?

Here are five related questions for further exploration:

1. What is the y-intercept of $f(x) = 2^x + 3$?
2. What is the slope of $f(x) = 10^x$ at $x = 0$?
3. How does adding a constant to a function affect its graph?
4. How do you find x-intercepts of exponential functions?
5. What is the derivative of $f(x) = 10^x$?

Tip: The y-intercept of a function is found by evaluating the function at $x = 0$.