I think it’s possible. I found a sample code on this thread that does that. On the recipe file, you can specify several items like this:
"produces": [
{
"item":"yourmod:item_1"
},
{
"item":"yourmod:item_2"
},
{
"item":"yourmod:item_3"
}
]
I don’t know if this still works with the current alpha, but you can give it a try