Just to add to Duncan's response, there is no way to incorporate Overwrite Web Layer into ModelBuilder because it isn't a tool unlike the Replace Web Layer Geoprocessing tool. If you would like to add the Overwrite Web Layer feature into ModelBuilder, the best way would be to create a script tool. The following may help you get started: https://community.esri.com/thread/216491-automate-overwrite-web-layer-feature-class
I am working on something very simialar. Here is a newer post that gives a python script tool you can download and drop in to model builder. It also has documentation on how to create the tool yourself so you can customize it and build others. Hope this helps!
