Little girls will always want to be Princess Sofia or any Disney Princess they fancy. Your princess will need a complete costume to emulate her birthday theme, need decors associated with the specific theme, a cake decorated with the princess’s colors and drawings. In addition, add some homemade crafts or purchase some with the particular birthday theme more so color coordinated.
On the other hand, if your baby boy is celebrating a thematic birthday party, he might prefer a super hero themed birthday party, football themed birthday party, or on boy-related stuff.