This is a well represented feature request in Revit. Autodesk recommends using Parts and Assemblies
https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/How-to-divide-a-fl...
https://youtu.be/vX0cnxBX0qk?si=BOn83G0hm4ZSouqf
You could look at the Precast Tools to get an understanding of panels and assemblies and hopefully these tools will lend themselves to other materials in the Future.
I have seen panels designed as families which are adjustable and have nested connections inside as per your image but these would be placed as individual items and need to be place manually.
You could look at the slab edges tool but you would still need to have individual slabs which is counter productive.
or
You create a family with elements in which replicate each connection but does not physically split the slab but would graphically look correct and you place it where required.
Jay Colcombe
Autodesk Certified Instructor
Revit Architecture & Structure Certified Professional
AutoCAD Certified Professional
B.Sc. Hons Civil & Structural Engineering
If you find my post interesting, feel free to give a Kudo.
If it solves your problem, please click Accept to enhance the Forum.