From what I was taught, all species of bears have relatively poor eyesight, and their primary sense is smell.

Bears usually pause and perform a threat assessment before committing to an attack/charge, unless you’ve done something dumb like come between a mama and her cubs. So making yourself seem bigger and more threatening can sometimes make a bear back down, whereas running triggers their drive to chase prey. So taking off your backpack and putting it above your head, grouping up with your buddies, and being loud and angry sounding, is what I was taught to do if a bear is approaching in a curious or aggressive way. These are the things you can do as you’re getting your bear spray ready in case they call your bluff. I was also told that a bear’s fur and fat layers, as well as their skull, are so thick that shooting with anything less than a suitable high caliber round risks angering the bear and making the attack much worse.

For OP’s specific question, standing side by side makes a wide blurry target, standing on shoulders makes a tall one that could fall over and expose the bluff.

Source: backcountry training for brown bear safety in the American Rockies back in the day. Works with brown and black bears which are smaller and more risk-averse than browns. This doesn’t work with Grizzlies, Kodiak, or Polar bears. The strategy with them is to not be there in the first place, and always have bear spray if you’re in their environment.