Hello everyone Me444 here thank me later I found out how to have unlimited build for a settlement on xbox1 without modding.

After you have maxed your size cap simply drop any random Scrap item on the ground that you can part with. Next select what you want to build. It will not show since your maxed out. walk over to the item you dropped and scrap it then boom you can build again 

Just sharing a nice glitch with the fam enjoy!! 

i seen it done that way and this way here that will work on xbox one, ps4 and pc

1) go to the workshop, open transfer, then transfer all your weapons over, close out the workshop when you are done
2) open transfer at the workshop again, this time take all the weapons back out, then close workshop (when taking the weapons back out, it does something to the game mechanics)
3) find a nice flat spot, then drop all the weapons on the ground
4) run back over to the workshop, this time open it up like you are going to craft, then run over to the weapons you drop, store them back to the workshop and watch the settlement size go down. (Don't use the keyboard key shortcut to open up the workshop, just run over and open it the normal way, not sure if it will mess it up if you use the keyboard shortcut)