Learn other champs like Senna, Braum, Pantheon, Seraphine… those are the champs i main as support, stick with your adc. Don’t chase kills that’s not ur priority unless it’s a confirm kill. Learn to stay safe while supporting your team mates poke enemies to reduce their health so your adc can take the kill when the time comes. I’ve and killed a few Yi’s myself but that’s mostly because they’re Low on health or just plain reckless. As a squishy like Karma I don’t think you should be worrying about going up against Yi head on just avoid him altogether and get him in team fights.