Ugh I posted a big thing and it disappeared.
How I'd define it personally is that it's the 'default'. By that I mean, it doesn't manifest itself by people going 'oh heck yeah you're a straight white guy here's some free stuff for you or whatever', it manifests in a lack of oppression that other people get. Women are way more likely to get sexually harassed, assaulted, or passed over for jobs. For many jobs, there's an unconscious bias against women for a couple reasons, which mostly boil down to 'the people doing the hiring are overwhelmingly older men, and even though they are not allowed to officially have gender based hiring practices, they instinctively think of men as more suited to certain roles.' (The inverse is also true for certain roles, it's just that nurse, cleaner and teacher don't pay as well as doctor, engineer or scientist.)
I'm less likely to have political parties run on a platform that people of my ethnicity or religious background shouldn't come to this country. I'm less likely to have people pass me over for jobs because 'my accent is difficult'. I'm less likely to be killed in custody. Because of how generational wealth works, I was statistically more likely to be born into the fairly well off middle class situation I found myself in.
Also, because I'm straight and CIS, there hasn't historically been legislation that supported the view that I was a mentally ill deviant who should be executed, (death penalty for sodomy removed in Victoria in 1949) or at least imprisoned, (sodomy decriminalised in Tasmania in 1997) or at the very least, that if if I hit on someone, that they could use that as a legal defence against murdering me. (Gay panic defence struck down in South Australia in 2020.) Also, there's not been any schools trying to get parents to sign contracts that state if their children come out as straight they can have their enrolment cancelled, but a school sure tried to do that contract about LGBT students about a week ago.
As to friends and family, it varies. Anecdotally, I tend to get on better with those who acknowledge it is a thing, but I think that's in part because there tends to be some compelling Venn diagrams regarding those views and the willingness to ignore science around climate change or vaccines, or support Trump as president, or say that suggesting we stop marginalising people is 'political correctness gone mad'.