Most door thresholds have this capability. Door manufactures use mechanisms like screws or sliding elements, this moves the threshold cap up or down. Thus enhancing the seal against drafts, moisture, dust, and insects. 

The adjustment screws are often hidden by plastic caps. Remove these to find the adjustment screw beneath. Adjust each screw a little as needed and check the seal with the door closed. 

A bonus is this can offer flexibility for sticking or sagging doors. One side of the threshold can be adjusted more than the other helping to match the level of the door slab.