If your players want to discover information, you don’t have to role play them asking every last person for it. Instead, take a 10,000 feet view.
It can take time and ability to discover information. The player rolls for the appropriate ability check, which determines essentially how long it takes for them to find the information (PHB 187). Persuasion if they have to talk to people, investigation if they are reading a book, etc. The better the roll, the quicker and more efficiently they are able to find the information out.
Keep in mind, it might take days or weeks of in-game time to find what they seek.
This method falls under the downtime activity of Research. One of the keys for downtime is that the character is doing it when not adventuring. So they might research, then adventure, then research some more before finding out the whole of what they seek.