Hi @Anonymous ,
Do you want to set up a Power Automate flow to achieve your needs?
Do you want to update the corresponding CDS Entity record based on the change of List Item in SP List?
Based on the scenario that you mentioned, I assume that there is no a Choice type column in your SP List, and there is a Option Set type column in your CDS Entity. The Choice type column and the Option Set type column have same available options, right?
If the Option Set column in your CDS Entity is a "Multi Select Option Set" type column, I afraid that Power Automate flow could not achieve your needs. Currently, within Power Automate flow, we could not update a "Multi Select Option Set" type field within "Update a record" action of CDS connector.
If the Choice type in your SP List is a Multiple Selections Choice column, and you want to save these selected options back to the Option Set type column in your CDS Entity, I afraid that Power Automate flow could also not achieve your needs. In addition, when providing a value for Option Set field in "Update a record" action, you need to provide a integer value rather than a Text value:

According to your scenario, I think Power Automate flow could not achieve your needs.
Best regards,