For Operating System Deployment, You need to have a PXE support. PXE Support can be enabled on one of the Distribution Points.
PXE support will allow clients to request a OS Deployment over the network.
Launch the SCCM 2016 Console and Go to Administration, Servers and Site system roles, right click Distribution point and click properties.
Click on PXE tab, check the box Enable PXE support for clients.
When the warning box appears, click on Yes. This will enable the PXE support for clients. This will install WDS role on the Distribution point.
Make sure that required ports are open on the firewall in order for it to work properly.
Select Allow this Distribution point to respond to incoming PXE requests and Enable unknown computer support.
Enabling unknown computer support, will warn you about the risk associated with it. If you are happy with the risk, Click OK.
After all required components are selected as shown in picture below, Click OK or Apply to begin PXE Support setup.
This completed the Adding PXE Support for Distribution points.