Good idea! Best way to meet people and develop contacts, I think. Have you considered the type of work you would like to do? My impression is that here in Swizerland organizations don't publicize volunteer positions as much as they do in other countries. Instead, you find an organization that interests you and then contact them to see if they would like you to come help out.
Have you had a look at the SRK website (in German and French only, I think)? Here's their contact form: https://www.redcross.ch/de/wie-sie-m...treten-koennen
Otherwise, you might contact local churches or your area's Gemeindezentrum. Here in Zurich there are GZs that have weekly language cafes staffed by volunteers with a knowledge of Italian, English, Spanish, etc. You act as the language "expert" and chat with whomever shows up - it's a great way to meet people.
Good luck and have fun.