In my experience of senior positions, they're typically ignored if you apply through Linkedin. You're better off going direct with a nice cover letter.
Do people seriously read cover letters. I've often debated if its worth the time ivestment.
I wouldn't write a cover letter unless the company explicitly asks me to, or unless I can add additional information that wouldn't be fit into the CV. For example, when I applied to Digital Ocean my cover letter was the correct place (in my opinion) to say that I've been a customer if theirs since 2014.
For the record, they were interested until I said I would have liked to work remotely (since they bragged extensively about remote work on their careers webpage).