There is no such thing as a "free full permanent version" of Revit 2020 from an official source. Autodesk does not offer its industry-standard BIM software for free permanently. However, they provide legal, fully functional free versions for specific user groups (students, educators, and trial users).
: For the first time, users could insert PDF documents directly into projects as 2D objects, allowing for quick tracing of vector data to create walls and lines. Path of Travel Tool Autodesk Revit 2020 Free Download Latest Version