New Here: Prepping for Interview

Hey all. I'm kinda new here. I'm planning to start prepping for interviews. I've been out of school for about 6 years (so 6 YOE) and honestly while I was in school I never fully understood Alogs and Data Structures. I'm currently a manager and looking to bump my TC. Just had a kid and want to provide more for him and set him up for a better life than I had. My background is Comp Eng and I am a full stack dev .Net stack. Little bit of angular and react. Also have some experience with Azure Dev Ops. Currently, I'm making 146,800 base and a bonus of 3700 last year. No stocks. Company also contributes about 4% per paycheck I believe to some sort of 401K plan for which I am now fully vested (about 40K currently). Am I making way below what is expected for my YOE and background? I've read a few posts on here about people's prep journey. I know about Neetcode Blind 75, CodeKarla and Sean's list. Also, might get the DDIA book. I came across freeCodeCamp on youtube. I plan and watching the Alogs and Data Structure course. Will that be a waste of time? Anything else I'm missing? Also, I more question how do people apply for so many jobs? Do you use a recruiter? LinkedIn? Glassdoor? or just go to the individual company sites? Any advice would be much appreciated. #tech #softwareengineer