To the extent that it doesn't disrupt other people's enjoyment of the game.
I flatly don't allow non-consensual conflict between characters. At my table, if the rogue wanted to pick the the pocket of another PC I simply wouldn't allow, period. Similarly, PCs cannot effect each other will spells like command/suggestion/etc.
Furthermore, I also do not allow PCs to 'stop' other PCs from doing things. For example, let's say that the Fighter wants to pull a lever/push a button/whatever, I don't allow another PC to attempt to stop them because they think it's a bad idea. There isn't even a "roll to see who gets there first" - people have agency over their characters and get to decide what they do, as long as it doesn't disrupt group cohesion.
If the aforementioned Fighter is pulling the lever just to be disruptive, I'm probably talking to the player away from the table to determine if they're a good fit for my game.
Yes, otherwise you won't be a PC in my game.
'No' and 'No, absolutely not'.
I have found it is very rare to find a group of people who are all interested in, and mature enough for, an impromptu live-action RP that has all the drama, backstabbing, and inter-party secrets of a novel/movie/play. The people I play with come to the table knowing they're a team and they all get a chance to pursue their own special quests/ideas and I expect the other players to support them.