For an iPhone 5s on iOS 12.5.7, bypassing the iCloud Activation Lock is possible because the device is susceptible to the checkm8 hardware exploit. Legitimate Methods
If you want, I can draft a concise “proof-of-purchase” email template to send to Apple Support or the seller. iphone 5s ios 12.5.7 icloud bypass
The iPhone 5s: A Blast from the Past
: Commercial software that often provides more automated "one-click" solutions for iOS 12.5.7, sometimes including signal/SIM support for a fee For an iPhone 5s on iOS 12
Contacting the Previous Owner: If purchased second-hand, ask the seller to sign in to iCloud.com, select the device, and choose "Remove from Account". No receipt
: Because the iPhone 5s uses the A7 chip, it remains vulnerable to the checkm8 exploit