Of course it is but things to consider.
Inform your insurance company. If you don't, they can nullify your insurance should you be in a crash.
Your car will look odd. Both the FR and Cupra sit lower than the S/SE. Even if you don't know this you know that a car just looks wrong. There is a grey ST sits along the street from me which has big wheels on it. At first glance you think it's an FR but it looks a big wrong. Then you realize it's sitting too high.
For what it costs to do these changes to the car you'd be as well just selling it and buying the better car. I'd rather have a car that has the go and not the look than the look but not the go.
You'll probably struggle to sell it. Most people do not want to buy modified cars. Yes, some do but most people want the usual low owners, full service history and as close to factory as you can get. I bought a modified car once, regretted it and I'll never do it again.