How does the baking time change if I scale up a cake recipe?
The following rule of thumb comes from week 6 in a Harvard University physics course called "Science and Cooking". I took it as a MOOC in the website edx (https://www.edx.org/node/8086).

And the rule is: double the thickness, quadruple the time. If it takes a minute to cook the first outer 0.5cm of the cake, it will take four minutes to cook the first whole cm.

So if you double your cake's size, try to start with multiplying the time by four, without raising the temperature. If the change is smaller, then it might take some rough calculations. But that's the general rule.

Here's the video of the specific part of the lesson that regards discusses the matter: https://youtu.be/fqyVZ5Ifmio