Definitely not. Wednesday is a made-up tale. It takes us into a fictional world filled with magic and intrigue. It's all for the purpose of giving us an engaging and enjoyable viewing or reading experience.
One way to develop their relationship is through acts of kindness. Maybe Xavier gives Wednesday a piece of his art that he made especially for her, which shows that he sees her in a special way. Wednesday, in turn, could protect Xavier from a bully at school. Another aspect could be through humor. They could start making inside jokes based on their strange experiences at school. As they get more comfortable with each other, they might even start to develop feelings that are more than just friendship. For instance, Xavier could find himself getting jealous when another student shows interest in Wednesday, which would be a sign of his deeper feelings for her.
There's also 'Wednesday and the Forbidden Art'. This fanfiction takes Wednesday on a journey where she discovers an ancient and forbidden form of art within Nevermore. It's full of dark undertones, which is very much in line with the character of Wednesday. The way the author describes the art and its implications in the context of the school makes it a really engaging read.
It's a blend. Big Wednesday incorporates elements of truth along with creative imagination. The story might draw from real events or people, but it's not a straightforward documentary-style account of actual happenings.