We are using CMS 12 by the way.

Since this is an OnPrem (as stated in the comments) you are better off using the Azure Graph API to get the information from SharePoint to CMS, depending on the complexity of your SharePoint installation this may be a gigantic task.

Now, automatic construction of content types may be possible using the new manifests (Content Definitions) in CMS but there are several concerns to be addressed before going there.

• Structure
  • How will the structure of all SharePoint sites be mapped to CMS? Or possibly, will all SharePoint sites be mapped or just a specific one?
  • Construct a map of your SharePoint environment and how the structure in CMS will look.
• Metadata, SharePoint has a very complex structure regarding Terms and Taxonomies, the Terms are "rich", and CMS does not have such complex Taxonomies. Will the CMS Categories be sufficient or do you plan to use any third-party solution?
• Internal references, SharePoint often use list lookups etc to enrich content items, this would be (sort of) equal to ContentReferences in CMS. A problem when migrating such structures is that you can only link or refer to items that exist. Hence you need to migrate in several steps adding on properties like content references when they exist.
• Documents, SharePoint is great at handling different types av documents while CMS is not, shall binary files be transferred or linked?

That's a few questions just to get you started. I've done a few migrations but typically end up setting up a structure with CMS with pre-specified content types, "synching" data from SharePoint using some custom-built sync tool which is able to map whatever's in SharePoint to CMS.