Bing Image Creator if you just want to create some images quick (free, Microsoft account required). It’s using DALLE3 behind the scenes, so it’s pretty much state-of-the-art, but rather limited in terms of features otherwise and rather heavy on the censorship.

If you wanna generate something local on your PC with more flexibility, Automatic1111 along with one of the models from CivitAI, needs a reasonably modern graphics card and enough VRAM (8GB+) to be enjoyable and installation can be a bit fiddly (check Youtube & Co. for tutorials). But once past that you can create some pretty wild stuff.