Here's a quick example of the practical zoom range you can get from the Olympus M.Zuiko Digital ED 12-40mm ƒ/2.8 Pro zoom lens. These were taken mounted on a Olympus OM-D E-M1X body, which has a Micro Four Thirds sensor (that is the sensor size this lens is specifically designed for).
When converted to the equivalent focal lengths at 35mm (or a full-frame sensor), the 12-40mm focal lengths on a Micro Four Thirds sensor ranges from 24mm to 80mm. So it covers from wide-angle to a mild telephoto focal length that would be a good choice for portraits.
Here's what it looks like in practice:
Accessories for This Lens
The Olympus M.Zuiko 12-40mm ƒ/2.8 Pro lens takes 62mm filters.
The dedicated lens hood is model number LH-66.