Authors and authority
A credible source will list the author or authors, and may also include some information on their experience and education. If their experience or education is not included, you should be able to search their name and find their credentials. If an author isn't listed, or if you can't find any information on the author, it might be an indication that the source is less credible.
What does it mean to be an expert?
Expertise comes in many forms. In academia, it means a person has an advanced degree (a Master's or Ph.D.) in their chosen field, and has a history of contributing to that field through activities like teaching, researching, and writing.
Does a chef need an advanced degree to be a professional chef? Nope! They may have a culinary degree, but they will also have a lot of experience working in a kitchen. Does a journalist need an advanced degree in economics to report on economics? Nope! But they probably need a degree in journalism or communications, and some background knowledge on their topic. Does a person who is food insecure need a degree in public health to describe what it's like to be food insecure? Nope! Their lived experience is enough to know what that is like.
The type of information you are looking for might influence what kind of expertise you want to turn to. 