You can create and define rules under Order Workflow Rulesets to automate the split order for certain business scenarios. This requires some configuration in order for you to create and manage rulesets.
To automate the split order under Order workflow rulesets, perform the following task.
For your convenience in creating rules, you can add the Order Workflow Rulesets tab to your default view as you would add any other object tab.
Add Split Order to the Action field in the Order Workflow Rule Detail page.
In Salesforce Lightning, go to Setup > Object Manager to edit the page layouts for the Order Workflow Ruleset and Order Workflow Rule Entry objects.