I try to clear the area around the Rex, before initiating the tame. Admittedly, this is particularly tricky in areas like Carno Island on The Island map. Keep an eye out, and deal with other dinos before the Rex can aggro on them.

oh we were in the Extinction, in some place there is a LOT of dinos

Sorry, I only just saw this message. If you're adventuring with a buddy, then they should be on wild dino duty. At the very least, to kite bigger beasts away from your taming target. It's okay to let the Rex fend for itself, if there's a chance you might hit it.

If that should happen, then you can leave the area, and then return to resume or restart the tame. I had an unfortunate shotgun pellet incident happen, while trying to help a Megatherium I was taming, to fight a Terror Bird. After I went back, the immersive tame was complete without issue.

引用自 Xilia Vield：

oh we were in the Extinction, in some place there is a LOT of dinos

If you're ever doing this on a map with Wyverns, I discovered that if you use their wing push, it isn't considered a hostile attack by the Rex. So you can separate them from the animal they're attacking, kill the animal and gain more favor. I've done that with two separate tames. However, be mindful that you are also pushing the Rex.

u need use trophy bait craft station, and craft the specific bait for rex and challenge him,
after u beat he will not attack u, then u drop another bait on he feet or hand feed when avaliable

引用自 DDragon：

u need use trophy bait craft station, and craft the specific bait for rex and challenge him,
after u beat he will not attack u, then u drop another bait on he feet or hand feed when avaliable

that was already done, since i was already in taming progression with it. even if you immersive tame any dinos after too much hit, it will turn against you