With a so-called "self-hosted blog" based on the software that you download for free from WordPress.org, you can of course start your blog immediately with your own domain.
One of the first "exercises" should be to set up two of your own email addresses with this domain: a public one such as info@ or contact@, which you also use for the imprint, and a non-public one that you use for your customer communication and which contains your name or initials - for example birgit@ or bs@. You then no longer need to use a freemailer address for business purposes.
You can use free cayman islands telegram screening themes (although I don't recommend it) and license and customize any WordPress theme you like. You can even find a theme developer to create your own theme for you - although this isn't cheap - and in my opinion isn't necessary given the thousands of themes out there.
You can (but shouldn't) install and use any WordPress plugin you want - many of them are completely free. You have no restrictions on what you can upload to your blog, neither in file format nor size (depending on your web host's contract, however).
There are no advertisements and you have full access to all your files and the database. So if you ever want to change your web host, you can do so without any problems.