Unfortunately, and although the V30 does have a dual camera on the back, this is not a standard feature for its camera (see article below, in the Dual Camera features section). Not sure if there's a 3rd party camera app that would allow this, but IIRC from the V20 LG didn't let 3rd party cameras access the second lens, so not sure if that would work. https://www.androidauthority.com/lg-v30-vs-galaxy-note-8-camera-features-801390/
Creepy stranger butt picture aside, while that works for selecting the right focal point, and for the most part, will have enough background blur effect with closer shots, I believe the OP wants the more aggressive background blur and single-subject selection of things like Live Focus from Samsung or Portrait Mode from iPhones, where even if the focal point is at a certain distance, only the subject will be clear and the rest will be blurred, even if at the same plane as the subject (blur would come from both the dual lens adjustment and further image processing, the latter being how Samsung allows for blur adjustment after the picture's been taken).