Tutorials Resources:

https://visualizingarchitecture.com/
https://www.ronenbekerman.com/architectural-visualization-tutorials/

3D Models:

https://flyingarchitecture.com/
https://www.cgtrader.com/free-3d-models
https://sketchfab.com/features/download
https://www.turbosquid.com/Search/3D-Models/free

GIS Repositories

https://www.naturalearthdata.com/
https://www.geofabrik.de/
https://opentopography.org/