It is absolutely fascinating to watch a bunch of adults verbally berate a teenager on the internet for asking questions. I hope you are proud of yourselves.
As for OP, sex ed should be required in school because a lot of people have completely stupid notions about basically every single topic involving sex, be it basic biology (not knowing how the body parts work, not knowing how periods work, not knowing what pregnancies entail, etc), to how to be safe during intercourse (condoms, preventing pregnancies, preventing wounds), how consent works (don't touch people that don't want to be touched, you have the last word about your own body and nobody else), to stuff like people having attractions and that those attractions don't necessarily are only towards the other sex.
Obviously this doesn't need to be taught at once on the very first day of school, but having it split up over a few grades is pretty much the perfect way to deal with it and to ensure everyone reaches a base level of understanding that's better than the US's current approach. Plenty of people still believe pulling out is effective birth control (it is absolutely not), believe that "sperm can't travel upwards" (it doesn't need to), don't know which hole does what on the other gender, and just so much more dumb shit. Anyone suggesting it's the parents duty to teach basic biology and ethics is setting up a whole bunch of teens for failure thanks to ill educated parents.
Personally I got my first class of sex ed around 9, which just involved basic anatomy of either sex, and none of the functions explained beyond basic "that's where pee (professionally called urine) comes from", "this is where babies come from", and then basically after every year it went into a little more detail about things. Waiting with the first parts of sex ed until age 13 or later is stupid, as girls can have their first period at 9 so that's a good place to start to hopefully catch even the earliest girls so they know what might be coming. I believe we talked about actual sex at around age 12 or 13, but by then we already knew all the body parts and what puberty entails for everyone, a solid foundation for a bunch of kids about to transform into horny teenagers.
Unsurprisingly out of our 3000 students only 2 got pregnant as teenagers during my 10 years there, compare this to seemingly 25 births per 1000 teens in the US and you can see what differences a proper sex education can do.
As for LGBTQIA+ issues, that should likely be handled in ethics or a special class, but also covered in history classes with how perception of it changed through the ages, considering none of those things are modern creations. Telling people that LGBTQIA+ individuals exist is as far from grooming as it gets, the point is to educate that it exists and give the kids the means to explore their own little minds a little. This gives them tools needed to express themselves properly, to their peers and their parents. This even benefits kids outside of the LGBTQIA+ spectrum because they, too, get the tools to properly express they're not part of it, or might even help them understand some of their peers that are in there a little better.