Applying a filter to filter or combining filters?

Is there a system for using filters in combination? Specifically I wanted to use Crop:Circle and Size and Position together. In this case instead of the closing to the center I wanted it to close onto a person head.

Also is there a list of what all the filters do? Some are obvious, but as someone relatively new to video editing many are a complete mystery to me.

Crop circle is not the filter to use. It can be moved with the Size and Position filter but the result will not be very good.

Use the Mask simple shape filter instead. Key frame the width and height parameters.

https://streamable.com/u32wo

Look at the project to see how it can be done.
Crop circle with Mask.zip (818.4 KB)

There is documentation category. https://forum.shotcut.org/c/docs
The developer is very busy with improvements to the application. Most of it is still under construction.

https://forum.shotcut.org/tags/c/docs/docs-english/filter

Documentation is a work-in-progress just like everything.

I do appreciate the answers, but I meant a list with a description of each filter. I looked at multiple filters in that list and there is no actual information.