Homebrew doesn’t have rules
Even if every single class that already exists follows an exact pattern that’s never been broken, you don’t have to do the same thing.
There just aren’t any rules for this, you can make whatever you want, however fantastical, overpowered, or complicated as you like. It may differ from how the system usually works, and what you should be doing then is justifying that choice.
If you’re going to give a class a meager two additional hit points, I would hope there is a good reason. It’s a small change and one people are likely not to even notice given the way every single other class is structured. If this is a vitally important aspect of the homebrew, it should be emphasized in the text and the change should be made clear.
In all honesty, I see this type of change adding confusion and for very little gain (+2 HP is very little). That doesn’t mean you can’t do it anyway, you can do anything you want, but you should have justifications for when you depart from the usual format of the system.