How do I disable “Send with effect “

Hello there GrahameL,

Welcome to Apple Support Communities. We're happy to help you with disabling this feature on your iPhone. Go to Settings > Accessibility > Motion, and switch off Auto-Play Message Effects. You can get more info on this function here:

Reduce screen motion on your iPhone, iPad, or iPod touch

Let us know if you have any questions.

Best regards!

Hi again GrahameL,

You're welcome! Please feel free to reach back out if you have any other questions, or run into any further trouble.

Take care and be safe.