If l make a new iCloud account will it delete everything off my phone

Just making a new iCloud account will not delete anything.

If you sign out of the old account it will ask if you want to keep all the data being synced to iCloud on the iPhone, you can answer yes to keep it.

With that said however, it's normally recommended to not make multiple accounts. If you have an issue with the current iCloud account, it would be best to resolve it than create a new account as that can lead to other more complex issues that may have no solution.