If the old laptop uses a hard drive, then first enable Filevault and let the encryption process finish. Then when you use Disk Utility to erase the drive it will destroy the encryption keys making it impossible for anyone to access the data on the drive. Otherwise you would need to write a single pass of zeroes to the hard drive.
If the laptop uses an Apple SSD, then a simple erase using Disk Utility will destroy all data on the drive since TRIM will cause all unallocated blocks to be zeroed automatically. I'm not sure how a non-Apple SSD will behave even with TRIM enabled since I'm not sure that setting is recognized in Recovery Mode or from a bootable macOS USB installer.
Here is what you should do when getting rid of an old Mac (many steps must be performed before erasing the Mac):
https://support.apple.com/en-us/HT201065