Enable sensor if consumption is low

Configuration
6

There’s literally an example in the docs I posted for you that you can tweak for your use case: Template - Home Assistant (home-assistant.io).

# Determine when the washing machine has a load running.
template:
  - binary_sensor:
      - name: "Washing Machine"
        delay_off:
          minutes: 5
        state: >
          {{ states('sensor.washing_machine_power')|float > 0 }}

My guess:

# Determine when the washing machine has a load running.
template:
  - binary_sensor:
      - name: "Some device not running"
        delay_on:
          hours: 3
        state: >
          {{ states('sensor.some_sensor') | float < 10 }}

You haven’t given us much to work from: You haven’t shown what you’ve tried, no entity names, whether you’re using YAML or the UI, etc. How to help us help you - or How to ask a good question - Configuration - Home Assistant Community (home-assistant.io)