Test a working title for length, clarity and how well it reads as a thumbnail, before you commit to a cover.
A good title is short enough to read on a phone screen, easy to say out loud and clearly signals the genre. Thrillers and fantasy often use two to four punchy words. Non-fiction titles are usually short, with a subtitle that explains the promise.
Search Amazon and Goodreads for your title in your category. Titles cannot be copyrighted, but a clash with a well-known book will confuse readers and hurt discoverability.