One of the workflow limitations is; it does not support access to its next related entity. One can only access the main entity or the related entities but not next related entity.
we have 3 entities Account, Contact and CustomEntityA.
Account is related to Contact and Contact is related to CustomEntityA. Account is not directly related to CustomEntityA.
If we want to update a field e.g. description on CustomEntityA on update of the description of Account, or if we want to update Account’s description from CustomEntityA’s description, we cannot do it with OOB workflow. We can either write plugin/customWorkflowActivity or there is another option without coding anything which is combination of Action and Workflow.