Below is a list of light bulb types used in 2018- FORD FOCUS lighting system, covering estate, hatchback and saloon 4-door vehicles.
Headlight bulb: low beam - H7 / high beam - H1
Fog light bulb: H8
Front indicator/turn signal bulb: PY21W
Rear indicator/turn signal bulb: PY21W
Tail light bulb: W5W
Brake light bulb: P21W
Light bulb sizes for other FORD FOCUS generations: FOCUS (MK1) / FOCUS (MK2) / FOCUS (MK3)