Hey!
Me and my partner are really open in every aspect of our relationship and one day miss secret did tell me she loved the idea of being in control as I'm usually the dominant. I'm no stranger to anal play as Iv always thought you can't knock things till you tried them and eventually we went from some butt play with fingers to small toys and then bought a strap on.
Initially it was bizarre for me as I have never been in a submissive role but this gave it more of a rush. The only thing I would explain to your partner is limits, if anything hurts then have a safety word or just let them know to stop. With strap ons it's hard to really judge how deep, fast and hard the giver is going so you need to have honest communication until your boundaries have been established. I would suggest getting an anal douche in case of any poop mishaps and also it makes everything far more comfy, and vigorous amounts of lube.
It's a great feeling being pegged and my partner loved the dominant side for a change, almost too much so I had to turn the tables after and make sure she knew I was still in charge ha. We have also tried using a strap on for double penetration and this worked really well in doggystyle and a few other positions.
It's a great adventure down anal road so be safe, have fun, be honest and know your limits.
Hope it all goes well!