Q.Killing bindweed
How? I have identified the roots and pull them out as much as I can, but I’m afraid when I pull them, I just break them into small pieces when make them spread more. I’m also adding a lot of topsoil to my garden with hopes of burying them further. Can I do anything else other then adding chemicals?

Here is an article that will help you.
The topsoil may slow them but they will continue to grow up through it.
https://www.gardeningknowhow.com/plant-problems/weeds/controlling-bindweed.htm