In the game you find the setting under Settings → Mouse/Controller → Mouse Sensitivity.
Conversion
CS2 to Apex Legends Sensitivity
In short: CS2 sens times 1. 1.2 becomes 1.2. For your own value, just edit the sentence below.
How to set it in Apex Legends
What changes when you go from CS2 to Apex Legends
CS2 and Apex Legends turn the same angle per mouse count. You can keep your number as it is.
The default field of view is almost the same: CS2 106.26°, Apex Legends 105.5° horizontal. The picture feels alike. For Apex Legends the field of view is only a rough guide, check it in the game.
In Apex Legends you can enter up to 2 decimal places. Use all of them to keep the conversion exact.
Common questions
How do I convert CS2 sens to Apex Legends?
Multiply your CS2 sens by 1. 1.2 in CS2 becomes 1.2 in Apex Legends.
Where do I set the sens in Apex Legends?
Settings → Mouse/Controller → Mouse Sensitivity.
Why does Apex Legends still feel a bit different?
CS2: 90° at 4:3, about 106° at 16:9. Apex Legends: Slider from 70 to 110 (about 105 to 106° horizontal at 90). Match the field of view as closely as you can; then the converted sens feels most natural.
Does this also apply to scopes?
No. The values are for hipfire. Zoom and scope sensitivities are set separately in the game.
Should I change my DPI?
No. Keep your DPI and only change the sens in the game. That keeps your feel the same everywhere.