IRL since you are cis and I asume you look masculine there is no need to specify your pronouns.
I disagree with this. It’s better not to assume or encourage people to assume pronouns. It’s better to use they/them when you’re not sure. Most of the time you can learn people’s pronouns contextually, by hearing how other people refer to them.
Otherwise, it’s better to use they/them unless you have evidence otherwise. Looks isn’t evidence. It’s not the worst thing to assume once and be wrong, but if you’re aiming for inclusivity it’s better to not assume