in the first room the speedrunner uses rocket launcher and entirely skips an area how can i do that?

triggers that spawn enemies are usually a thin walls, when you get on rocket it moves you a little, so you skip that trigger. For the beginning you can try it with freezeframe, find where trigger is, stay as close as you can, fire freze rocket and jump on it, then unfreeze. If everything done correctly you will skip trigger and area. In this clip speedruner makes this with instant rocket riding by shot and whiplash at the same, can't give any advice about this, there is need of right angle, timings etc, so only trying to recreate this by yourself

Here, made this for you for better understanding

sorry for the very late response but thank you so much @biba_dzibun