I'm going to assume you no longer live near family, or are not close to them. I was severely depressed for over a year where I lived alone (across the country from my parents) without pets after a painful breakup. Getting a remote job and moving back closer to my parents/cousins/grandmother helped the most, but other things that help(ed):

* Going to restaurants with bars (like diners or sushi bars) where I could attempt to make small talk with servers

* Regularly going to the gym. Cliche, I know, but at least 3 times a week at the same times and I started becoming friendly with other regulars who had similar schedules. If you get friendly enough with someone, don't be afraid to ask if they wanna get food or beer after.

* Volunteering (cliche as well, but it helps) at the same place once a week. I volunteered for a high school bringing near-spoiled produce from local supermarkets to their horticulture club. There's loads of ways to get involved, but maybe start with your city/county's website to look for volunteer opportunities, ideally ones where you see the same people every time. This lets you build trust and community with folks who are often from different walks of life.