You can get a reasonable read on how competitive a keyword is just by manually reviewing what's currently ranking for it.
Look at Who's Currently Ranking
Large, established sites dominating the results for a term generally signal higher difficulty than a mix of smaller, less authoritative sites.
Check How Thorough the Top Content Is
Weak, thin content ranking in the top results can indicate real opportunity, even for a term that might otherwise look competitive.
Weigh Difficulty Against Realistic Timeline
A term that's genuinely difficult for a brand-new site might be entirely realistic for one with more established authority.
Next step: Use the SEO Audit to see how your existing pages currently perform for terms you're evaluating.