Treat an LGBTQ+ character the same as any other
If you wouldn't treat a heterosexual cisgender person that way, don't treat an LGBTQ+ character that way. It's that simple.
For example, if you have a wedding between two lesbians, write it as you would a wedding between two heterosexuals. Also, if you have a transgender character, you can mention them having surgery or taking hormones, but you don't have to linger on the fact they are transgender.
Does it honestly change much? It doesn't generally impact the plot much.
"Oh, by the way, I'm a bisexual," Alex says.
"Great," the protagonist says. "What does that have to do with stopping the Dark Lord?"
It only changes the plot where sexuality or gender is relevant such as:
"By the way, I'm a lesbian," Alex says.
"Great," the MC says. "That doesn't help us stop the Dark Lord."
"No, but I'm attracted to you. I'm confessing."
"By the way, I'm gay," Ryan says.
"Great, how does that help us stop the Dark Lord?" the MC asks.
"I can try seducing him?"
"By the way, I'm transgender," Stacy says.
"Great, how does that help us stop the Dark Lord?" the MC says.
"Because the Dark Lord is a manifestation of my internal struggle with understanding my gender identity and the weight of society pressuring me to be a girl."
"What-what do I even say to that?"
It only creates a difference on specific circumstances, situations where gender or sexuality are relevant.
Stories thrive on conflict and drama both internal and external.
What if the character thinks they like guys but learns they like girls instead? Now they have to break up with the guy and explain the truth. Great external conflict.
What if a character thinks they are a girl but begins transitioning into a boy? They now have to rediscover themself and question what it even means to be a boy or a girl, or if those words hold meaning at all. Great internal conflict.
Just treat an LGBTQ+ character with the same respect you should treat any character or person you meet in real life.