Hi Pratiksha,
Through my test, I find that it is not general option set type field.
In fact, it is an entity, and each option in the list is each record of Survey Answer Option(msdyn_chatansweroption) entity, which is N:1 relationship between it and survey question (msdyn_surveyquestions) entity.
For example, I create a survey question record that answer type is ‘option set’ and it has four options.

When you direct to the survey question record, the four options is listing in the sub-grid, if you click add button of the sub-grid, it will open Survey Answer Option quick create form.

So if you want to add or delete one option in the list with the flow, you need use ‘create new record’ or ‘delete a record’ action that associate with ‘options’ survey question.
Regards,
Leah Ju
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