I doubt your child will wear them regularly, but can’t hurt to bring a pair. When our girl was about a year old I bought her a pair, with elastic strap, half due to the sun and half due to the wind and dust when I took her cycling. She doesn’t wear them regularly, but next week we’re spending a few days down south at the beach and I’ll be sure to pack them. Much more useful in my mind is a good hat, which our girl (now six) has a few of that she wears regularly in the summer. But it can’t hurt to bring some shades, too, especially cuz your kid, like ours, will likely enjoy wearing them as a fashion accessory.
Btw, on an occasional basis, I can’t imagine they’d be harmful as lots of reputable companies sell them. Surely if they were hazardous they’d be facing lawsuits in the US.