I developed my own, but I would say I was influenced a lot by the Jamie Gold Beat sheet and stuff I learned from this book https://www.amazon.com/Write-Romances-Revised-Genre-Writing/dp/0898798671
I know, paperback, right?! Old school! It's been a few years since I actually held it in my hand (I have it in storage somewhere) but I still remember a lot of the lessons in it, from creating character sheets to plotting out the story. I used it a lot in my fanfiction writing days!