Yes you can use Shiplap outside and it will be just fine.
Shiplap was originally used outside as siding on houses and other buildings and recently the shiplap has been used indoors on walls.
However while Shiplap can still be used outdoors it's best to paint or at least waterproof the Shiplap siding material so that it repels water and prevents it from rotting out too fast.
Most Shiplap should last easily for 50 to even 100 years even when used outside as long as the Shiplap is installed and maintained properly.
Painting the Shiplap every few years or at least every 6 years or sealing the Shiplap with Thompson Water Seal or other water seal products can help extend the life of the Shiplap and other wood that is used outdoors.