Hi my iPhone x max have locked SIM card

Carrier Lock:- Request your iPhone’s original Carrier to unlock your iPhone and if they agree and do it, then you may know the further process here --> How to unlock your iPhone for use with a different carrier ...

This is an Apple user to user forum, no one here has locked your SIM card.

You need to contact the carrier the card is locked to and ask them to unlock it.

SravanKra has already given you the instructions on how to do it, here they are again -

How to unlock your iPhone for use with a different carrier - Apple Support

To be able to use any SIM across the globe you must have "No SIM Restriction" against Network Provider Lock. Please refer to the pic below.