A plug can create a feeling of fullness or pressure. But it does not guarantee prostate stimulation or an orgasm, and it is not essential for pleasure. Sometimes other things matter more: pace, trust, control over movement, and knowing that you can stop without having to explain.
If you decide to try it, choose a toy with a flared base and use lubricant. You can begin with external touch; penetration does not have to be the goal. Before starting, agree on a pace and a simple signal that means stopping immediately. Before passing the toy to a partner or moving it from the anus to the genitals, wash it or change the condom.
There is no need to push through pain to achieve a result. Stop and change what you are doing, or end it. Curiosity about sensations is a personal choice, not a test of masculinity.