Mutli Application Calling Model From Shared Site In Single Installation Codeigniter 4

To do what you want, your model must have a namespace other than the default one.
By default, models have the \App\Models namespace.

PHP Code:

// You need to add namespace in application 1 and application 2 configs
'Source\Models' => 'path/to/app/Models/'

// change class to
namespace Source\Models;
classSettings { }

// And in both applications call 
= new \Source\Models\Settings(). 


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In general, it is better to move the model into a separate module, which can be connected in both applications.

Thank You @iRedds. I update the answer in the https://stackoverflow.com/q/74457092/6786634
I have separate the module. I created a shared/Models folder. So the shared model can be access from both application 1 and 2. 
Now everything is working.