I've linked this contract's official documentation at the end of an earlier comment which I made here:
AFAIK, the most widely used access-restriction mechanism, which also happens to be the oldest one and the simplest one (probably the reason for it being the most widely used one), is
Ownable.
If you navigate to that webpage, then you'll see that it tells you where to import this contract from:
import "@openzeppelin/contracts/access/Ownable.sol";
You can also find it by browsing through the node_module folder in your project:
