Yeah. Have a text field ouput the email of the person field.
Then after that have a workflow trigger on edit and add a branch by condition. Condition should be determining if email property of person field equals text field. If so do nothing. If not then do whatever you need it to do. Be sure you update the text field with new email for next change from a user to be verified.
Not sure what your source list or library is but another strategy I have used is:
Using a sharepoint list for managing ‘cases’ where a case manager (person field) is assigned.
The list has nintex forms for O365 and on the nintex form if the case manager control is changed, I have a form rule/variable which compares the control value against the list/column value and then sets a boolean field of ‘case manager changed’ to True.
The workflow is then run based on item modified and condition of ‘case manager changed’ = true. Make sure that the workflow sets the ‘case manager changed’ to False when completed.
I like @Gavin-Adams idea better. Stealing this. Bahahaha.