You make a few big assumptions. Especially that if you have a sibling you will still have a fairly close relationship with them in adulthood.
My family have always been very spread out across the country and the world. I never really had grandparents in the same way other kids do. I do think thats contributed to why I live so close to my parents, but I accept thats a luxury for now and may well change.
As for my own sibling. Well suffice to say we have no relationship as adults and it is highly unlikely to change. As sad as it is.
No matter what you do to try and bring up your family as close, you can't predict the future and events that may rip you family apart or whether your kids will react to being a close family by 'spreading out to find freedom' or to take an amazing opportunity. I honestly don't think, how you parent always makes a difference as it ultimately down to what your children value and the decisions they make.
Your own experiences affect how you feel about family, but you can't expect your family to know, appreciate or agree with your values and preferences in the long run even with the best will in the world.
Having more children, is never going to be the guarantee of stopping them feel the loneliness you might have felt. And actually your expectations and demands to have a close family, could ironically end up having the opposite effect, if you aren't careful about it.
The rosy picture postcard idea of family is a little dangerous. Better to enjoy what you have and just go with the flow rather than trying too hard to overthink it.