Hi Alessandro,
1. for change size I have to manage by CSS
* If you mean size of site title and tagline, try following code in Appearance=> Customize=> Additional CSS:
/* For Site Title Font Size */
#site-title {
font-size: 40px;
}
/* For tagline */
#site-description {
font-size: 25px;
}
2. for color and font I have to use appearance panel
* Yes that is the case.
But: to change type of characters (example: bold, italic) have I to use CSS also?
* Yes, you need to use CSS. For that, you can view some tutorials via google, or ask us here in support.
Is not possibile by catch themes insert all this preferences in Appearance panel (maybe in the next update)?
* I am afraid this is not a feature that is worth adding. These can be solved by simple lines of CSS code.
Regards,
Pratik