need to reset passcode without erasing phone

That is not possible. You are learning the importance of a good back-up plan. Follow the instructions in the blue link above your name on this page. If you are running iOS 15.2 or later, see this link...

How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support

JemmiBlack wrote:

how to reset passcode without erasing phone

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By remembering the passcode otherwise continue here If you forgot your iPhone passcode - Apple Support

You can’t. If you forget the passcode you have to erase the device to reset it.