As an example, the OEM e3k 90deg antenna has -2deg of electrical tilt. Does LP online take this into account? e.g. if I select this antenna and insert -2deg tilt, is LP taking into account the -2 electrical tilt on the antenna, bringing my total tilt to -4deg?
LINKPlanner online is using exactly the same 3D antenna patterns as the desktop version and where the sector antenna includes electrical tilt, this is taken into account in the pattern. Any mechanical tilt entered in the Antenna Tilt box is in addition to the electrical tilt, so yes if you add -2 deg mechanical tilt the total tilt will be -4 deg.