WordPress toolkit/Agency Standards

Hello everyone! I wanted to pick the brains of those who have been in this field for awhile. I am currently working for a small agency and I am the only front end developer. My previous position (first out of college) was at a large company. Marketing team of 30+, 7-8 front end developers, 4 web developers. I am now part of a team of 12 and find myself needing to know a whole lot more than I do lol. I am trying to develop a toolkit and set some agency standards for website maintenance. Everything we do in-house is WordPress. I’m just curious what you experts are using to help with workflow, site migrations, penetration testing, your favorite plugins, etc. Any information would be helpful.