There are three axes against which you can pivot your career as a product designer: where do you work, in what industry, and on which products?
Do you work for yourself (freelance), do you work directly for a company that offers a product (in-house), or do you work for a company that helps other companies (consultant)?
Freelancing offers the most flexibility but a less consistent income, and in-house provides a consistent income but less variety of work. Consulting offers a variety of work but without deep industry knowledge.
There is product design work to be done in nearly every industry imaginable: Advertising, Automotive, Computing, Cybersecurity, Data, DevOps, Education, Entertainment, Finance, Gaming, Government, Healthcare, Human Resources, Insurance, Life Sciences, Manufacturing, Media, Non-Profit, Real Estate, Retail, Restaurant, Supply Chain, Telecommunications, and Virtual Reality.
As you work in these industries, you learn more about them; some you will find interesting, others less so. If you find an industry you like, you can become an expert.
The most significant delineation between industries is B2C versus B2B. In a B2C industry, a business offers a consumer product: Amazon, Netflix, and Starbucks are good examples. In a B2B industry, a company provides a product to another business: Microsoft, Oracle, and IBM are good examples.
Some companies are both. Adobe, for instance, sells software to both consumers and businesses.
In a B2B industry, you are more likely to focus on UI elements like color and layout to appeal to everyday consumers. In a B2B industry, UI elements are essential but often take a back seat to workflows, which tend to be more complicated.
Some industries lend themselves to particular product design problems. Big Data, for example, often involves tables: how to load, sort, and filter them. Finance (or FinTech) often involves data visualization and e-commerce workflows. In Education, Healthcare, and Government, you are often tasked with modernizing outdated technology.
Finally, there are three main categories of products: mobile applications, web applications, and none of the above. While many companies have all three, B2C companies tend to have mobile apps, while B2B companies are more likely to have web applications. A lot of exciting product design happens on other screens: thermostats, appliances, kiosks, gaming consoles, TVs, and watches.