I have one idea, but just didn't try it. Assuming I want to roleplay for acocial person who get moral and psychological trauma after his exit from the shelter and he just want to be at home in Sanctuary and no anywhere else. The question is... How to leveling with crafting before you get 14 level to building magazines? And is it possible to leveling in one settlement not going across the sideline?

I don't get what you mean. What do you mean by "leveling in one settlement"?

Just go outside, play missions, and you'll get EXP.

Someone has done it, its sounds pretty boring to me but that is another story.

I mean to get an Exp just inside the settlement. Not outside.

Build stuff

Well you can build until you run out of materials. Then you can start a new character I guess since that one would be finished.

But why even concern yourself with leveling if you are not leveling the settlement?

Build a settlement beacon, and a slew of scrapping benches. That should give you stuff to play with once the initial supply starts running out.

I got to level 10 by only scrapping and building in Sanctuary straight from the Vault. Had to go get extra stuff from Red Rocket and carry back, but it is easily done. not sure about lvl 14. that seems to become a steeper level increase after 10.