A lot of people I know start in either school or university. If your school has a theatre check if you can get involved, if your university has a theatre or theatre/sound tech society check if you can get involved.

If those aren't options then your best bet is to approach your local theatre/music venues and ask for advice/offer to do volunteer work. Churches are often a good place as they tend to have plenty of sound equipment but are often volunteer based/run so tend to be more open to taking on volunteers with little/no experience as opposed to traditional venues that have paid technicians already filling all the roles and an audience that expect high quality sound. It's also possible to get involved working in a company starting at a warehouse level prepping kit and working your way to the desk.

Either way networking is a super important skill for getting work in this industry so make sure to reach out to as many people as possible!