Absolutely! No matter which hand is comfortable for you to write, the techniques and rules are the same. For very slanted scripts like Copperplate lefties usually are in advantage, as their natural position of the pen points to the angle needed. So, all in your favor! You can use a straight pen holder or on oblique with a flange on the right side. Some lefties also prefer working with obliques with the flange on the left side, just like for the right handed persons, but it’s up to you to decide which works best for you.