Reviewing what terms your competitors are targeting, and how, is entirely doable without paid tools, just by reading their content and page structure carefully.
Review Their Page Titles and Headings
The specific phrases used in a competitor's titles and headings often reveal exactly which terms they're targeting.
Look at Their Site Structure for Topic Priorities
How a competitor organizes their navigation and categories reflects what they consider their most important topics.
Note Gaps, Not Just Overlaps
The terms and topics a competitor hasn't covered are often more valuable to discover than the ones they clearly already own.
Next step: Use the SEO Audit to compare your site's current visibility against what you find in a competitor's content.