Read the small print on the agency sites, many disclaim any guarantee of services discussed or published on the site for any girl.
The agency will only likely confirm what's already published, none are likely to promise more than what's listed.
Once you're with the agency girl you will then have to confirm what you want is available. As long as it's on her published likes it will be inclusive, if she happens to have others unpublished then they may likely be extra.
It didn't used to be so uncertain but that was in the days when many of the decent agencies had decent, "honourable" management who would usually look after you if you had an issue with services promised or (not) rendered. Suspect too many arseholes tried to exploit this and now a lot of the agencies are very unaccommodating, it's no longer a standard of service and reputation that they take pride in they are just (expensive) call takers. It's why many choose to use "indies" through AW et al.
Don't forget that some save your number and build a history of who you've seen when. This makes them subject to GDPR but fuck knows if they're doing anything to ensure their responsibilities are met.