import Calendar, E-Mails, Tasks, contacts

Thanks! Vasils link explains the different ways to do it the Microsoft way! Usually a hybrid is set up or cut over method used, but as the documentation explains, the on premises domain must be present in office 365 ( primary domain if I remember correctly ) also hybrid goes away since you are cutting all ties and only use a new domain!
Have a look at any third party tools like bittitan or such! There is a licensing fee of course but it’s very competent tools And often very user friendly

Adam