Most business facing documents in D365FO if you are ok with the basic layout you can add a little bit of color but putting on a report logo. There is an option in the legal entity setup to allow you to upload the logo. This will display on documents where it has been designed to display like the sales confirmation etc.
Here is a quick overview.
D365FO Update3 (7.0.4307.16141)
If you want to do a lot more advanced formatting you can use the SSRS development tools or there are 3rd party solutions that plug in.