While romance is not nearly the main focus of Life is Strange: True Colors, there are two options for romance throughout the game. Throughout the game, your two closest friends, Steph and Ryan, will be there for you and are the only people you can get steamy with. Here is how to romance then.
To romance either Steph or Ryan, all you need to do is interact with them plenty. Whichever one you make a stronger impression on will ask to meet you on the bar rooftop during chapter four. For example, we tried going for a no romance run and still had Steph want us to kiss her on the rooftop.
Throughout the story, there are moments that you can flirt with each of them. For Steph, she asks you if you are into girls while playing foosball, or you can offer your hand in marriage to her character during the LARP for the stone. As for Ryan, you can hug him and have a moment in chapter two at the accident site. Just get closer to each other by interacting with who you want.
Before you play guitar on the stage, you can grab a rose and give it to either Steph or Ryan and push towards that person inviting you to the roof. If you would rather not get too attached to either character, you can take the just friends approach and only offer hugs or handshakes to them while on the roof.