How to multiply base system clock using .xdc constraints in Vivado
No, you can't.

The .xdc doesn't control the design, it informs the tool of the physical reality of the board. Setting the clock to 100MHz or 200MHz doesn't change the design in any way, the tool will always verify that your design works with the constraint you inputted. If you forget to input constraint or input wrong constraint, you get in a situation where the tool tells you the design works when it doesn't (or vice-versa).

You have to use the clocking wizard. The input clock to the clocking wizard comes from an oscillator on the board (or another clock generated by a clocking wizard), in your case the 100MHz oscillator clock. You set the wizards's parameter for the desired output clock frequencies (2x time input clock), and voilà!

There are several reference design for your board, you should look at them to see how the core functionalities works.