Approach #1

Using forge install

Openzepplin

Ref https://docs.openzeppelin.com/contracts/5.x/

forge install OpenZeppelin/openzeppelin-contracts

Update/add remappings.txt

@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/

Approach #2

Using npm

npm install @openzeppelin/contracts

Update/add remappings.txt

@openzeppelin/contracts/=node_modules/@openzeppelin/contracts

<aside> 💡

You can also run forge remappings to confirm things are working as expected

</aside>