About radius it depends how many flights pass your area. More flights make more requests to FlightRadar. There is request amount restrictions if you dont have flightradar subscription. So the best way is to test by our own
Just use url in markdown like
type: vertical-stack
title: Flightradar24
cards:
- type: entities
entities:
- entity: sensor.flightradar24_current_in_area
name: In area
- type: conditional
conditions:
- condition: numeric_state
entity: sensor.flightradar24_current_in_area
above: 0
card:
type: markdown
content: >-
{% set data = state_attr('sensor.flightradar24_current_in_area',
'flights') %} {% for flight in data %}
<ha-icon icon="mdi:airplane"></ha-icon>{{ flight.flight_number }}({{ flight.aircraft_registration }}) - {{ flight.airline_short }} - {{ flight.aircraft_model }}
...
[Open FlightRadar](https://www.flightradar24.com/{{ flight.callsign }})
{% endfor %}