IEEE conferences managed thru EDAS system are usually interfaced with Crosscheck service which automatically highlight to reviewers the percentage of detected similarity for the paper to be reviewed with existing papers.
Unfortunately, this service can only be accessed thru the conference admin console. I checked with IEEE support who confirmed that such service cannot be accessed by an end-user but only activated as a paid service for a conference.
Also, I think, I remember that another API called ithenticate is sometimes used.
My question is: As an author, not as a reviewer, How would I know what is the computed resemblance percentage of my paper to existing works prior submission?