Keeping coding style consistent at the work place

To give a little more context- I'm a junior dev at a company and the codebase I'm working with has alot of legacy code. We're not using nodejs. Front-end is html, css, plain javascript, asp, angularjs, php, jquery and back-end is .NET. The codebase does not have a consistent coding style which makes reading code and debugging more strenuous than it needs to be.

We are using VS Code and Sublime. I want to make the coding style consistent for all the developers by doing something that auto-formats the code on save. It would be great if we had something that would give error messages (like a squiggly red underline) for dead code, unused variables in the code base or some problematic patterns in our code. I'm not sure how well eslint would work since we do not use nodejs.

I may be able to use a .editconfig file but like I mentioned before the codebase consists of a wide variety of languages and maybe there's an easier way instead of specifying the coding style for each programming language we are using in a .editconfig file. Or I may be looking at this in the wrong way.

I'm not sure how I will be able to achieve this with the php and asp files. Any advice/suggestions will be highly appreciated. Thanks!