Architecture Diagram

you can uses Visio to draw the network
you can get the vision stencils for sccm2016 in the following link

https://gallery.technet.microsoft.com/SCCM-2012-R2-Modern-Visio-0265ad92

all the best

Creating architectural diagram, you should do it yourself using Visio or some kind of tool. Meanwhile considering your requirement the architecture is simple and you may require 4 -6 servers (vms). One for SQL DB  or two SQL cluster with one instance, One SSRS for SCCM, one SCCM server with roles in it and SCCM console server if still you want to split. Incase if you have two location, have secondary site server. Also it depends on how you want to download and push the updates. If you want to control from single site then you must look for secondary site or a simple DP will do ofcourse. The server with 32 GB RAM and 8 core vcpu with enough disk space for OS 200 GB and Data drive for storing the ContentLibrary 300 GB. For one server it can supports above 10000 clients, hence you have two sites, so two SCCM site server will do.

Thanks for the reply which is helpful but do you guys have the sample diagram though?

Apologies for the delay. Thanks for your help and I appreciate it.