What punishment did pliny impose on those who insisted they were christians? was he thinking about being more or less severe toward them?

The Roman Emperor Trajan saw Christians as a threat to the unity of his empire that's why he gave Pliny an order and authority to punish the Christians through a letter. As a punishment, Christians are beheaded.

Pliny is reluctant to do the task, so he gave the Christians an opportunity to be saved and deny their religion. If they refuse for the third time, they are deemed to be executed. - ahnnahly