Here's a playful and colorful design idea for a birthday text incorporating a child cartoon and a number effect:

Typography: Choose a fun and whimsical font that complements the playful theme of a birthday celebration. Opt for a font that is easy to read and has a youthful and energetic feel. Some font options you can consider are:

Josefin Sans for Happy birthday 

Arial for the Number

Bubble Bobble cocomelon font

Color Palette: Select a vibrant and joyful color palette to bring the design to life. Consider using a combination of bright and pastel colors, such as:

Pink: Represents sweetness and adds a feminine touch.

Blue: Brings a sense of calmness and balance.

Yellow: Symbolizes happiness and joy.

Green: Evokes freshness and vitality.

Orange: Adds energy and enthusiasm.

Layout and Composition: Experiment with different layouts and compositions to create an engaging design. Here are a few ideas to consider:

Cartoon Character: Integrate a cute and playful child cartoon character that relates to the birthday theme. Place the cartoon character next to the text, either holding or interacting with the numbers.

Balloon Numbers: Create the numbers of the birthday age using balloon shapes. Each number can be filled with different colors or patterns to add visual interest. Arrange them in a way that they appear to be floating or tied with strings.

Confetti and Streamers: Scatter confetti and streamers around the text and numbers to enhance the festive atmosphere. Use different colors and sizes to create a dynamic and celebratory effect.

Visual Effects: Add special effects to make the design more engaging and dynamic. Here are a couple of ideas:

Drop Shadow: Apply a subtle drop shadow to the text and numbers to give them depth and make them pop from the background. Adjust the opacity and distance of the shadow to achieve the desired effect.

3D Extrusion: Give the text and numbers a 3D effect by extruding them slightly. This can be done by adding shading and highlights to create the illusion of depth.

Remember to keep the design child-friendly and age-appropriate by using soft edges, friendly facial expressions on the cartoon character, and bright, inviting colors.

Once you have finalized your design, consider incorporating it into birthday invitations, party decorations, or digital greetings to add a personalized touch to the celebration.

Have a fantastic time creating and celebrating!