Network simulation in Chrome (or every web browser based on Chromium project like Brave, Edge etc) help developer to test their website under poor bandwidth like 3G.

To throttle a connection and simulate a bad bandwidth in Chrome :

1. Open Chrome Devtools by Right clicking > Inspect or Control+Shift+J or Command+Option+J (Mac)
2. Go to Network Tabs
3. Click on the No throttling dropdown, as in this example:

   

4. Select Slow 3G preset to throttle bandwidth to slow, you can also add a custom preset by clicking Add...
5. Clear cache and hard reload by Right Clicking on the reload button and select Empty Cache and Hard Reload.

The website will reload simulating a slow connection. This is how to throttle bandwidth.