I searched for this for a long time and there is no information almost on the internet. I will leave the answer for someone who is looking for. I bought a cheap X96 Mini box, possible fake box by the price, still a S905W processor.
With the Libreelec 9.0.2 I get full TrueHD and DTS MA HD audio on my receiver. Just enabled the Pass Thru and all started to work.
Just remember you won't see the receiver show DTS-MA or TrueHD. Just the PCM but the audio is full HD.