How can I unlock my iPhone SE after finding it?

What kind of lock?

1) iCloud: Activation Lock - Activation Lock for iPhone and iPad - Apple Support - This is a security feature so only legitimate (e.g., not stolen) use of devices is possible. Read this support article about how to remove Activation Lock --> How to remove Activation Lock - Apple Support - If an activation lock was put on a device, only the owner of the account that applied the lock can remove it. Get them to remove it or return the item for a refund. If you are the owner, see the part at the end about asking Apple to reset the device.

2) Device lock: If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled, read this support article if you are using iOS or iPadOS 15.2 or higher --> If you forgot your iPhone passcode or your iPhone is disabled - Apple Support or here if you do not meet the criteria for the previous method--> If you forgot your iPhone passcode or your iPhone is disabled - Apple Support

If your phone is Activation Locked, enter the Apple ID and Apple ID password that it is asking for. You say that it is your phone, and you found it, so it should be asking for your credentials.

How to remove Activation Lock - Apple Support

If the phone is not Activation Locked, but is in another security lockout state (because someone else guessed the wrong passcode too many times, then left the phone where they found it), you might have to reset the phone and erase everything on it, with the help of a Mac or PC.

This will presumably at some point require you to supply the Apple ID credentials associated with Activation Lock.

What message is on your iPhone screen? Did you have the phone in Lost Mode? The more information you provide the better able are we to help you.