"All accepted papers will be published in the conference proceedings and will be recommended for publication in IEEE Xplore." The quote was taken from a conference site. Does this mean that accepted paper will definitely be published in IEEE Xplore once accepted, or does that mean that there is a chance only?
If it is an established IEEE-sponsored conference, then I would expect that it means they will definitely be published in IEEE Xplore. Typically, the IEEE simply transforms the conference proceedings directly into an IEEE Xplore collection, and that is the official archival proceedings of the conference.
The only publications that typically do not make this transition are those which are not presented at the conference (e.g., the authors don't show up), which the IEEE does not generally allow to be published as part of the final proceedings.
I recommmend you to be careful. There are a lot of spam or predatory conferences, and some claim to be, or claim they will be, indexed in some more or less "prestigious" collections. They use that to lure authors.
You could check whether the conference was indexed last year (and the year before). You can give the website, some here may know.