Whenever you fetch tenants using an eloquent query, you'll get returned an instance of Spatie\Multitenancy\TenantCollection. This class extends from Illuminate\Database\Eloquent\Collection so you can use any of regular collection methods that you know and love.
In addition to the regular methods, TenantCollection provides two extra methods: eachCurrent and mapCurrent. Both these methods work like the regular each and map methods, but in addition they will automatically make the tenant the current one.
// the passed tenant has been made current
Tenant::current()->is($tenant); // returns true;