This page explains how to go across tight-ropes in Xenoblade Chronicles 3.
As you’re traveling around Aionios, you may notice tight-ropes or zip-lines scattered around. Try as you might, you can’t go across them since nobody on your team is a circus acrobat. In which case, you’ll need to find somebody who fits the bill (or close).
How to Recruit Juniper
The Hero you need to recruit is Juniper, from Colony Tau in the High Maktha Wildwood. You’ll encounter her during a mandatory Hero Quest near the beginning of Chapter 4.
Getting her to join you is pretty straightforward. After surviving Juniper’s initial ambush, simply continue further into the High Maktha Wildwoods. The game will make you follow her trail, but really, there’s no other way she can go.
When you catch up with Juniper, it’ll be at her colony. Despite attacking you, she’ll allow you to enter her colony. Once inside, head to the Ferronis at the back to trigger the next event. A group of monsters will appear in front of the colony entrance–dispose of them and Juniper will see the light.
How to use the Rope Sliding skill
Having recruited Juniper, you’ll obtain the Rope Sliding skill from her. You don’t need Juniper in your party to use this.
To use this skill, simply approach the tight-rope/zip-line in question. Your character will automatically step onto the rope and slide down. You don’t need to do anything else and don’t worry about falling off. Although if you’re feeling daring, you can jump (but don’t move the control stick or you might actually fall!).