Just because there happens to be a rainbow in the image? I'm not sure where you're getting this at all... There's absolutely 0 reference to LGBTQ content here.
Seems very clearly 'the universe is laughing at how small your range perception is' to me.
/edit, I missed OPs title... Yeah. Not sure what they're going for there.
I don't think classic SMS does this, but RCS and IMessage both do. SMS has 'delivery reports' (ie, the carrier will let you know when they succeed in transmitting it to the phone), but not actual read receipts.
Well, since you asked so nicely...