@hadilq for young children especially, transition is a matter of using a different name and pronouns and making cosmetic changes such as haircuts and different clothes. None of this is permanent. When they start to hit puberty, they may start puberty blockers, which delay puberty to allow them more time to make decisions and actually *prevent* irreversible things from happening (puberty is often extremely emotionally damaging to trans folks as our bodies are further changed in a direction that feels fundamentally wrong).
Your understanding of what transition looks like for trans children is pulled from what right wing voices want you to think, and it's not accurate to our actual experiences.