Disabling attention detection option will reduce the time Face ID needs to confirm your identity before unlocking iPhone X. Follow below steps to disable Face ID attention detection and turn on attention-aware feature.
How to Disable Attention Detection to Speed Up Face ID on iPhone X
Step 1: Open Settings > Face ID & Passcode. Enter your passcode to proceed.
iOS Settings Face ID and Passcode
Step 2: Scroll down to ATTENTION section.
Step 3: Toggle Require Attention for Face ID switch to Off position.
iOS toggle off Require Attention for Face ID
Step 4: Click OK on the confirmation screen.
OK to confirm disable Face ID Attention Detection
Step 5: Toggle Attention-Aware Features switch to ON position.
Toggle to enable Face ID Attention-Aware Features