@Coding Enthusiast Thanks for being more precise and correcting me. I would like to clear up few more things from what I have read.

This part is false.

G is not exactly a "constant" and is not derived from the curve. G is one of the point on the curve that we have chosen as the "generator" of the curve. And that means multiplying any value from 1 to order of G yields another point (not a string of characters!!) on the curve which would be your public key. And that is the basic of asymmetric cryptography.

So, you do say that they are not constant. But from what I have read in Mastering Bitcoin Book, the author says that "G is a constant point and they are always same for all keys in bitcoin."

G is a constant point called the generator point,

Because the generator point is always the same for all bitcoin users,

This is false. Legacy transactions don't have higher size, they have higher weight.

Thanks for clearing it up. I was completely unaware of the weight, although I have read that segwits fees are calculated based on the virtual size of the tx.