Understanding layers and recipes when trying to install a utility with yocto

I am extremely new to yocto and struggling with some of the basic concepts. I currently have a build running in QEMU, but it is missing some things that I want.

I have found a binary I want (suppose, bc) at https://layers.openembedded.org/layerindex/recipe/96/. Its part of the openembedded-core layer. So do I need the whole layer or can I just steal the .bb recipe? It seems like a lot to clone all of the openembedded-core layer just to get a single utility from it.

If I do need the whole layer, would the next steps be:

clone openembedded-core into my yocto project directory
add it to a list of layers (BBLAYERS)
add bc to IMAGE_INSTALL
source oe...
bitbake ...

Solution

So in the case of openembedded-core, It was already in my image, so I dont need to clone it again. However for a completely new layer it seems you do have to clone the whole thing.

The steps I described were generally correct.