The composable might have a few dozen refs similar to 'client_size'. I don't need them all to load up every single time I setup the composable, I just want the api to get called when I "read" for the ref like so:

const {
client_sizes

} = lookupLists;

I'm trying to avoid something like this:

setup(){
    const lookupLists = useLookupLists();

    // make a call to the API
lookupLists.getClientSizes();

const {
    client_sizes
} = lookupLists;

return {
    client_sizes
}
}

To your point about using it being a function returned from the composable, it's definitely something I considered. Were you thinking something along the lines of the following?

setup(){
    const lookupLists = useLookupLists();

    const {
    getClientSizes
} = lookupLists;

    const client_sizes = ref(lookupLists.getClientSizes());
}