If you are interested in the Women's Erotica niche..
One of the largest of the online Women's Romance retailers is celebrating Earth Day by providing a free book every day until April 22.
I just grabbed today's title and am sorry that I didn't know about it earlier (I missed getting the freebies for Apr 1 and 2 LOL)
https://www.allromanceebooks.com/index.html
No affiliate links here, I am just a long time romance and Women's Erotica reader ;-)
This retailer carries Romance and Women's Erotica -- I don't know exactly what they will be including in the freebies, however, even if these are just Romance, they will be a good resource for you to familiarize yourself with the larger Genre...
EDIT- It looks like they are offering both Romance and Women's Erotica. The April 1 selection is a BDSM Romantic Erotica selection
You do need to open and account, but it is free.
There is a scrolling slide show for all of the books and at a glance, it looks like there is a fairly broad spectrum being offered...I am seeing some I know I will want and others that don't interest me ;-)
OK, I just grabbed yesterday' title for free also... It looks like it may be an error in the shopping cart.
In any event, enjoy!
Tink