Every library I've been to in every town I've been to had Sunday hours. This includes New York City and its surrounding suburbs, Buffalo and its surrounding suburbs, several towns in Conneticut and several more in Toronto Canada and its surrounding suburbs.
Multiple libraries in small town Iowa do not have Sunday hours. Just to hazard a guess at the nearest place to have a library with Sunday hours probably requires a minimum 60 mile drive.
While most of the 70+ branches are closed Sundays, there are some 8 or 9 that are open from 1-5 on Sundays. E.g. the branch on Robertson, a few blocks south of Pico.
The hours for all branches are on the following page; to find the ones open on Sunday, just search on the page for:
Even my university library has sunday hours.