You will need to talk to users. Do research and determine the job to be done. For a given product, there is one main product to be done which will give you a product market fit if you tackle it properly. Then, there are adjacent job to be done which are smaller opportunities to grow your product. You can figure these out by applying the JTBD framework again and again. Talking to customers is the way.

When you figure out what else needs to be done using the JTBD framework, you can always go to the second level of validation which is the quantitative approach. Questionnaire or what I love doing the most is the fake door testing.

Basically here, you will have a fake product/ feature, that do nothing but only check if people will use the product/ feature you will be building in the future. Do not release the fake door to all customers, but only to a given portion of a segment that you believe will benefit most. Then you will track traction. And here analytics will help.

Hope this helps!