No. You cannot change the color of the notification light in LG Q6 Plus.
Yes, LG Q6 Plus does have the VoLTE.
LG Q6 Plus SAR value is as follows:
SAR Value (Head): 0.72 Wkg@1g
SAR Value (Body): 0.455 Wkg@1g
Yes, LG Q6 Plus does have the FM Radio.
Yes, LG Q6 Plus does support Miracast.