It's a non-issue being blown into a partisan one for political points. Library usage has been declining for decades. Most kids don't even take out books. If kids are seeing things you think are objectionable, I assure you, it's via their tablets, smartphones, and computers. It's from Reddit, 4chan, Twitter, etc. Not the local library.

Additionally, we should not trample on the First Amendment just because some speech may be objectionable. Going down the road of regulating objectionable speech gives power to the State to use arbitrary measures to censor speech it doesn't like. Sure, you may be okay with this now because the current people in power are those you trust, but you cannot always guarantee this going forward.