Blind[1] is a decent community to get a glimpse into what employees truly feel about employers, get referrals and overall tech career advice. It can get rather toxic and troll-ey at times, but you can filter that out to focus on the useful stuff. [1] - https://www.teamblind.com/
Cold application is fairly useless in today's age and time. A referral puts your application much ahead in the pool so that a human actually reads it.
Blind used to be a tolerable place until they made it exclusively US-centric. Importantly, I really loved their side product - Rooftop Slushie - where you could have resume reviews, interview prep, and get trusted referrals for a small sum. They seem to have closed that though.