I feel like there are natural settings for making friends.

E.g.

- Frequenting the same restaurants/stores (HT earlier sibling comment)

- Joining clubs/communities/churches

- Parents of kids’ friends

- Networking: Friends of family / family of friends / friends of friends

- Workplace (obviously)

I feel like this is how friendships/relationships happen more organically vs. the OP’s suggestion of talking to “someone waiting in line”.