Anal play is a learned skill. Comfort is the goal, not endurance.
Start small, go slow
The first plug or bead set should be smaller than you think. The body adapts; comparing to porn is a recipe for pain.
Lube generously, always
Unlike the vaginal canal, the anus does not self-lubricate. Use more lube than feels necessary, and re-apply.
Use a flared base
Anything that goes inside must have a flared or T-bar base. Non-negotiable for safety.