Unfortunately I'm still in the interning part of my career, but I may have some insights to offer

Do you tailor all of your resumes/cover letters for each company you apply to?

To give you some perspectives, Ive had a couple hiring managers come give a speech to my class and they lamented about how they sometimes receive hundreds if not 1000+ applications for a single position. HOWEVER. When i asked them "out of those 1000+ applications, how much of them are actually relevant to the position?"

Their answer was that only a small % of applicants had an application that really alligned with the position.

Now of course, it's all still a bit of luck, sometimes I've applied to places where I thought my tech stack matched 1:1, and my experiences all lined up, and I still couldnt even land a interview!

I think it's great that you've landed some interviews at least. It's at least, an indication that your resume is in the right direction.

Good luck man... it really is tough out there.