Apple might reset a device if you can prove to Apple's satisfaction you are the owner. However, Apple will not do so if Lost Mode is set on a device which may have been done by a scammer if a person signed into their device with scammer’s account.
Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. This is done online* at: Activation Lock support request - https://al-support.apple.com/#/additional-support Apple says, "Proof of ownership documentation is required," but does not provide many details in the article as to what is acceptable proof. Prior to this official service Apple typically required the original receipt** issued by Apple or an Apple Authorized Reseller. Note that while this will let you get use of the device again, it will not help you with lost access to an account.