This post is mostly based off of how to create pacing within sentences and paragraphs, rather than the whole story, or even whole chapters. It’s more of a line-level thing.
If you’re trying to create a faster paced scene, focus on your verbs. Make them specific and nuanced to whatever action you’re trying to portray. Where possible, also structure sentences so that the emphasis will be on the verbs instead of the nouns.
If you’re trying to write a slower scene, focus more on the nouns. Whereas verbs are inherantly action-based, nouns are inherantly more stationary. Where you can, sentences to put more emphasis on the nouns, and keep verbs simpler. This will pull attention away from the action making the scene possible, and focus it on what is unfolding around the person doing said action.
“I scurry down the hall, peering through every gap and hole in the cracking walls, beseeching them to yield more information than I'm actually entitled to. They remain unyielding. The Red Legion prepares for war in the rooms above, the floors trembling with their movements. As warriors run and shout and curse, my seconds slip by, taunting me as they pass. It’s only a matter of time before someone discovers my presence, and reveals me for what I am: a spy, and a traitor.”
“I walk down the cold stone passage. The cracks and gaps and holes in the walls might as well be my eyes; it is through them that I can see the outside world for what it is. A warzone. Not the paradise it's made out to be. In only a few hours it will be the resting gound of countless soldiers of the Red Legion. But my time is running out. I'm a spy, and a traitor, and this world has no room for either. Soon, my spirit will join the ones left on the battlefield."