Microsoft Account Migration and Windows 11 Setup

I need assistance with several tasks related to my Microsoft accounts and Windows setup.

Tasks include:
- Remove my old Microsoft account and replace it with my new one, ensuring no loss of information.
- Retain: Emails and contacts, Files and documents, Calendar events
- Possibly help with backing up existing data

- Update my system to Windows 11
- Set up a branded SharePoint site

Ideal skills and experience:
- Experience with Microsoft account management
- Proficient in Windows 11 installation
- SharePoint site setup and branding expertise
- Data backup knowledge

I need this done ASAP.