assigning benefits to a player (how ? )

[Sempiternal115]

In the custom games (CIV6) I play with friends we have a "world congress" we roleplay outside the game with an own ruleset behind it, and I wanted to ask if it is possible to add some modifiers to a player without interfering with any of the vanilla game mechanics, just as an example in our rulset the founder of a religion has the possibility to become the Pope. So if I would assign this player a series of benefits for being the Pope (for a limited time period ) how would i go about it. Is it possible to dettach it from all other mechanics like policy cards and goverments ?