Can Bicep be used to do what this Azure CLI script does?
az storage container policy create \
--container-name $containerName \
--name $policyName \
--account-name $storageAccountName \
--account-key $accountKey \
--permissions $permissions \
--start $policyStartTime \
--expiry $policyEndTime
No.
It's not possible in ARM (see Azure Blob Storage Container Stored Access Policy with ARM). Bicep is just a compiler that translates bicep code into ARM code that is used then to do the deployment.