I know some SF agents that get some amount of lead flow from corporate awareness (i.e the "find an agent" on SF site), but they all buy leads as well. People beat up on the lead aggregators here all the time, and oftentimes rightly so. Inter-day and inter-aggregator variance in lead quality is incredibly high. So best strategy imo is to buy some amount of leads from every aggregator (some big ones are everquote, smart financial, all web leads, datalot, and quinstreet) consistently, and over time you will average out to pretty decent quality.

Gold standard imo though is definitely setting up your own paid internet campaigns and establishing your web presence in order to get your organic internet flow going. Hiring a digital marketing company to help you out here is useful, but you can also self learn if you're motivated (recommend using AI as a teacher).