We have a custom mobile app in development and one of the issues we have is retuning a picklist that references a Global Value Set when logged in as a Community User. 

When trying to access the field: https://domainHere--sandbox.cs40.my.salesforce.com/services/data/v46.0/tooling/sobjects/GlobalValueSet/0Nt32000000XZCm
We get the following error: 

<Errors>
<Error>
<errorCode>INVALID_SESSION_ID</errorCode>
<message>Session expired or invalid</message>
</Error>
</Errors>

Is there an additional permission needed at the profile level for Community Plus users?