Wordpress should be avoided like the plague if you care about code quality at all. It actively encourages bad code and this will never change.
PHP programmers being conditioned to write low quality code due to their experience with things like Wordpress or other legacy bespoke codebases that aren't built on top of good programming practices is a real problem, and using a modern framework alone won't solve that problem, but I think Symfony in particular deserves credit for generally trying to steer people in the right direction. If you're just starting out writing complex applications in PHP, by using Symfony with PHPStorm (and possibly other code quality tools like PHPStan and php-cs-fixer, though PHPStorm already has decent static analysis and formatting built-in), watching the SymfonyCasts tutorials and being open to learning new ideas, you will likely end up writing at least moderately decent code because almost all of your programming environment will be pushing you in that direction.
Of course, if you just hired a straight up incompetent developer, they will likely end up writing unmaintainable spaghetti no matter how much they're pushed in the right direction, and there's definitely a high risk of that when hiring PHP developers, but I feel like there's an equally high risk for any popular high level language nowadays. Especially Javascript, there seem to be tons of self-proclaimed "front-end developers" out there who literally only know how to copy-paste React code and don't actually know much Javascript or CSS at all.