There are a number of cameras that run on battery and hook to the internet that are pretty easy to install and set up. I wouldn't call any of them a security camera, but if you just want to see what's going on outside by picking up your phone and swiping, they work pretty good.
If you have power outside, you can swap out a light for a camera and hard wire the power. I have one that replaced a flood light and lights up with motion (like the light did), but includes a camera. I think it's called the Ring Floodlight Camera.
If you want a true security camera, you probably need to be more specific. IMHO, a security camera is hard wired and the video is stored on site. A bit more complex.