Understand that SEO for escort agencies its just like SEO for any other websites.
Here are some things you can do:
Use keywords on your website ex: "your city" escorts, escort agencies, escort service etc... Also use long tail keywords.
Refresh your page content often.
Gain referrals from other adult websites or escort directories.
Use meta tags in your content.
Stay up to date on the latest SEO techniques.
This is the website I been working on in a very competitive city. High Society Girls

As I worked in an escort website for over 10 years I can tell you the. First do on page SEO, add proper keywords, mata tags and description. All photos should have Alt text. Than start building quality backlinks from adults directories.
Here is the website that I been working on and we rank high in Toronto with many important keywords. Toronto Escorts