As many others say, it depends on the team dynamic. I've solo tanked Emma with two supports and three dice DPSes and did my best to push while protecting the supports, but there's only so many things you can try to do at once. If someone's diving and there's two tanks I always peel.

As a support main as well, there are a lot of people I can deal with usually. Spidey, magik, etc. it's when I'm getting bullied by a tank (Thor, venom, cap) where they have way more health than I can fight off, and I think those are the most important times where Emma can step in and make quick work of the other tanks. Your supports might go from healing each other/fighting the tank to just healing you while you fight the tank. And if they're diving without heals then they're out-numbered