No. LG Q6 Plus does not have the fingerprint sensor but it does have the face recognition lock.
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 support OTG.
Yes, LG Q6 Plus does have the ViLTE support and you can make video calls.