It was a Chrome problem if I set in the print preview no margin the problem is solved and the ticket takes the hole of the width. But it leaves a high white space on top margin I can't solve. Someone with the same problem?

About logo, yes I am talking about putting my company logo on POS ticket.

Thank you so much Thierry.

Hello ! Ticket in POS is in XML file. If you are familiar with HTML syntax then you can scroll xml file in the point of sale module and there is <t t-name="PosTicket"> section. From there you can change your ticket contents. You can simply put <img> tag and you can add image/logo also.