The vast majority of software development work outside of startups and the FAANGs is cleaning up someone else's garbage, usually without enough budget allocated to be really thorough about it.
It's a toss-up as to whether your management will be receptive to any plans for migrating over to industry best-practices or not.
If are an "A" employee, and you can't handle working with "C" employees, do yourself a favor, and ask to look into the code base at the interview, then decline if you notice too many bad smells. Otherwise, you will have plenty of future work teasing things out of the big ball of mud, fixing them, and then throwing them back into the blob.
Half of all code-writers are worse than the median. And the median coder will happily copy-paste the first code that works into six different places, rather than spare a thought for future maintainability. Then they move on, you get hired, and will have to discover for yourself that the same broken code is in six-different places, now with subtle differences due to lazy bug-fixes.
Most companies can't compete with FAANGs on salary and benefits, and can't compete with startups on coolness factor. There will be some cargo-culting. Your co-workers will be less skilled than you, but will also have more seniority. You may, in fact, be able to do all their jobs by yourself, in less time. Resist this temptation.
How does this sound? Do your own job the first 2 hours or less of every workday, and then slack off while looking busy for six. Repeat until retirement. Mediocre companies won't reward you for being a better developer. They just don't know how to measure it. And they don't have former developers with still-current skills in management. The way to translate your former expectations over to a different kind of company is to look for a CTO that comes from a similar background as you, and shares those expectations. Other companies don't even know what good code looks like, or how much it costs--even in 2020, after 40 years of software gradually worming its way into every other kind of business. They're probably still using the Excel spreadsheet created by the co-founder in 1992, with all the VBA macros in it, and source control faked by making copies of it with different dates in the file name. It works, so why not?
If those software best-practice process requirements are not enforced from the highest levels, all those sloppy, below-median coders that get hired will drag the company standard down to what they can handle, or, even worse, turn the practices into pointless cargo-culting. Those code reviews could be overly focused on tabs vs spaces, or ensuring that names are in camelCase rather than snake_case, and putting try-catch blocks around code that does not throw exceptions (to name some examples that may or may not be actual anecdotes from my personal experience).