I have a Samsung q8f and while admittedly they suck formatwise I am under the impression that its able to handle dd+ and at least 5.1, possibly more chanels, and decode and output as 4.1 or 2.1 or 2.0 or whichever it actually plays it as.
But, if I have a file with sound better than dd+, if i ‘downmix’ and output as anything other than 2.1 the tv does no processing and just play left and right channels. (and admittedly I have no idea if the 0.1 channel actually gets played)