Adult Website not indexed

Hello,

I know this isn't for everyone, but I have recently acquired an adult/porn website.

The previous owner has said it is indexed in Google & Bing; that is untrue. A further look into it, the site was 'requested' index back in 2017, and only about 4 pages of just under 150 pages are indexed as they are more like adult games.

I am new to indexing, servers and coding/meta tags.
The Bing guidelines didn't offer much help, and any help or guidance would be very much appreciated.

Thank you.