TL;DR: A wide range of Microsoft Excel courses are available to take for free on Udemy ... or simply learn something new.
Microsoft Excel is free to use, with limitations. For the cost of a Microsoft 365 subscription, you get a whole lot of power.
Udemy is an online learning platform where you can access ... However, if you already have a decent amount of experience with Excel then feel free to try your hand with the more advanced courses.