get a filesystem ready on the new drive, mount it to /mnt/ (for example) and then cp -a everything. You could also use rsync. Or clone the entire harddrive with ‘dd’ and afterwards grow the partition if it’s a bigger hdd.

If you just want to replace the OS you can do manual partitioning on install, keep your /home and just overwrite the OS. But do a backup anyways since mistakes do happen.