exterior door to landing mininum height
Yes, the maximum vertical threshold height is 7.75” at a LANDING, if it’s not an accessible unit. That is to say, from the top of the landing to the top of the threshold it can only be 7.75” max. (So, the distance from top of landing to top of floor must be less.) (See ICC 1008.1.6, Exception)
The distance could be zero, so your requested 4” is acceptable.
Btw, a landing is required to be the width of the stairway or door which ever is greater and a minimum of 36” in the direction of travel. (See ICC 1008.1.5)