Will my SIM card from my iPhone 6s fit an iPhone 11 Pro?

Shantee1976 wrote:

Will my SIM card from my iPhone 6s fit an iPhone 11 Pro?

You can transfer your account from your 6S to your 11 Pro just by moving the SIM card over. But since the 11 supports eSIM you may be better off activating it with the eSIM. See—>Using Dual SIM with an eSIM - Apple Support

Both use nano-SIM cards.

Learn which size SIM card your iPhone or iPad uses - Apple Support

Whether this is a good idea is a different question.