Can you give me extracurricular activities ideas on animal activism and how can I develop my application theme as an animal activist
Animal activism is a pretty broad category. The list of animal rights organization with Wikipedia pages is quite long. What have you done to date to express your passion for animal activism? Which organizations have you already worked with? What specific area within animal rights are you most passionate about?
Based on the answers to those questions, you can inquire about volunteer opportunities with the relevant organizations linked on the Wikipedia page.
How this fits into your application will depend on the answers to the questions above, as well as why you find this work personally meaningful, and how you intend to grow as an animal activist in the future.