Is there a chance my sister could be trans?

Before anything, yes, I know the best way to know is to ask directly, but I wanted to hear some opinions first. So, Ive been noticing some stuff, like the other day I was talking to my mom about how is a popular head canon that Saiki Kusuo is a trans character, and mentioned his shape-shifting powers, and how he changes from male to female sometimes and she inmediately said "I'd love to do that", my mom panicked and almost jumped to ask my sister if she was trans, but she didn't say anything (my mom grew up in a pretty homophobic household, but she's doing her Best to unlearn that, she knows I'm pansexual, and is fine with me dating any gender, but I haven't come out as non binary because her views on gender are still sort of complicated) so I instantly stepped in to calm her down and just saying how Saiki could transform into anything, back and forth, trying to shift the conversation because honestly, I personally would have hated to come out after a reaction like that, and there has been some stuff, also my sister relating to Jax (tadc) who is now pretty much confirmed as trans, and she has access to a phone, where I often see how she draws characters and add pride flags to them, including one time where I just found pride flags on her notebook, but the one I've seen the most is the trans flag, which could mean nothing, but today I was going through her phone to check the alarms and noticed one in particular that said "get up or you're a woman" which, I really can't find another explanation to.

I know all of that is kinda silly to be taken as proof, but I have my doubts since that Saiki incident, and over all, I still want to ask directly, but I wanted to ask here: What would be the best way to ask about it? I don't want to scare her by saying something like "I wanna ask you something" or "I want to talk with you" as parents do because it's genuinely awful (in my experience at least 😭)