Where do you get clip arts for presentations?

I see some really nice presentations here and there with amazing clip arts, pictures, etc.

I wonder if there is a source to get such clip arts, public domain or paid, as a bundle. Or those presenters are drawing and making the presentations themselves.

Long ago, when I was young and more into presenting there were the bundles that one could buy and add to MS PowerPoint and use freely. I do not know if that is still the case or if it has changed since then.

If the presenters are mostly drawing their own clip arts, what hardware and software are the most commonly used?