i-tec USB-C Travel Adapter PD/Data Guide D'instructions Et Mode D'emploi page 8

Click on Gather Windows: using this option you can choose the settings of the corresponding monitor –
Scaled (offers available resolutions), Rotation (Standard, 90°, 180° and 270°) and Refresh rate (if offered).
Notes for using the adapter with monitors:

Working on the connected monitor when the Mac monitor is closed is possible with the power
supply from the grid (there are some limitations when using a HDMI monitor on older versions of
Mac). When the power supply is from the battery, the use of a HDMI monitor is limited by the Mac
(in some situations in case of problems with displaying it is possible to use the method described in
the following paragraph).