Yes that will work no problem.
You could in theory already fit the new switch with the stacking cables in the back to included it in the loop. And them get the switch online and add it to the stack.
Officially however you should first get the switch online on it's own and then modify the stack to include that switch.
Make sure your stack will not exceed 8 switches total since 8 is the limit.
You can freely mix same family switches inside a stack. So any MS250 model will stack with any other MS250 model (24, 24P, 48, 48LP, 48FP).