They don't lol.
The last thing they'll see.
The only thing that will get Jiren in danger is his weird trait of letting people hit him.
If he stand there and then Flash speed steals him and Sentry starts going all tentacle monster on him, plus the other two pour the power on, he may find himself in trouble.
Then he powers up a little and wipes out the galaxy.
I dont know. Jiren was standing in one spot letting powerhouses pound and blast on him throughout the show. They'll have to be pouring in more power than they have been displaying in comics. Red hair Goku was getting punched by a being who's punches was warping reality and Jiren is magnitudes more powerful than Red Hair Goku.