You can try, but I don't know whether I'd bother.
If she's reasonably intelligent and wants to circumvent your enforced protections it'll take her less than an hour. If she wants to look at unsuitable sites then she will. I don't censor Tom's internet access at all (he's also 11). He knows never to install anything without my say-so, never to open emails from people he doesn't know, never to sign-up for anything without permission and never to give his email addy or name without an OK from me. If he sees people shagging, so what. I think he's a sensible kid and I just have to trust him.
A good hardware firewall, a good and up-to-date AV and Windows Defender are essential
By their nature all protection utilities end up blocking lots of perfectly innocent sites which happen to have trigger keywords in them so can be quite frustrating.
Most of the millions of easily accessible "unsuitable" sites are fairly straight sex, about which these days, she probably knows more than you, at least theoretically.
If you feel you must put something in, then HostsMan -
http://hostsman.abelhadigital.com/ - is free and as good as anything. Not only can you block pr0n, but it will also block a lot of malicious sites, which IMHO are a far worse threat than endless tired images of people copulating.
