A lot of this can come up organically, but the trick is not to shy away when it does. The other side of that trick, is NOT to get complicated, you don't have to have all the conversations at once - answer the question or deal with the issue in front of you in the moment, you don't have to deal with it all today.
I started teaching DS about consent as a toddler. he has always been taller and heavier than his peers so, for example, I vividly remember him bumping into other kids at a softplay on the jumping castle thing and me having to point out to him that he's a lot bigger than his new little friend so actually, he needs to be a bit more careful.
As the children get older, there's natural conversations - no, you don't have to hug that person. No Johnny, you can't stroke Diana's hair if she doesn't like it. Be gentle with the kitty cat, he's only little and he might be scared. etc etc etc.
Re porn, that's harder, but it helps that we weren't shy about having the basic sex conversations relatively young, then quickly established some best practices (consent, condoms etc) which made general chit chat about porn a bit easier. I do worry now that he's a teen and these convos don't come up so organically anymore whether we did enough in the time when we WERE his key source of info but I hope we did. We certainly were a lot more forthcoming that many of his friends' parents.