Hello Carolyn,
Along with the links that Dan Mentioned, here is a Learn Lesson that comes with data and step by step instructions on how to split existing parcels:
https://learn.arcgis.com/en/projects/split-parcels-in-a-parcel-fabric/
You can also use that provided data to do a host of other workflows as well using Tasks that come installed with Pro.
On the Insert Tab go to Task, click the down arrow then choose Import and Open, then click Parcel Fabric. Then choose Record Driven Workflows.
You will need to map a few layers to that Task Item and then you can run through step by step workflows in the parcel fabric.
Please reference this documentation that explains how to remap those layers and has other links to documentation on how to use Tasks: https://pro.arcgis.com/en/pro-app/latest/help/data/parcel-editing/use-tasks.htm
Thanks,
Jason Camerano
