Should I make everything I can constexpr

I have a conception question. For a homework I need to create a rectangle class that holds its width and height as doubles. The more I look at it, the more I want to make it constexpr : the ctor and most functions follow the guidelines for a constexpr. But on the other hand, I'll never use it where you normally use constexpr (in template arguments, etc.)

I'm quite new to constexpr and advance C++ stuff and I was wondering if I should do it even though I might not use it. I don't know if I'm clear, I hope I am