You can try looking on specialized graphic design websites. Some popular ones are Shutterstock and Freepik. They often have a wide range of clip art options.
This is a rather strange and potentially disturbing combination. It's hard to determine a specific meaning without more context. However, any depiction involving Nazis and such sensitive subjects should be treated with caution and respect for historical facts and human dignity.
The key to creating a caricature for a wedding anniversary is to capture the couple's love and happiness. Start with simple shapes, then build up the details. You could also incorporate inside jokes or memorable moments into the drawing. Use bold lines and vivid colors to make it stand out.