How can I unlock my iPhone sim side

If you mean that your phone is locked to a carrier other than the carrier of your SIM, only THAT “other” carrier can unlock the phone. See:

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

If you mean that your SIM is “locked” by a SIM PIN, see this article and contact your carrier:

Use a SIM PIN for your iPhone or iPad - Apple Support

Then contact your carrier, only they can unlock it.