How can I import openzeppelins contracts if the inherited contract uses a compiler versions higher than 0.5
Welcome to the community
Can you give some more detail about what you are trying to do?
I assume that you may have a token contract using Solidity 0.6 or 0.7 whilst the Crowdsale contracts are written in Solidity 0.5. In that situation you may want to keep your token and your crowdsale in separate projects.