public interface IResourceManager
    {
         IStringLocalizer Localizer { get; }
    }

 public class SchoolResourceManager : IResourceManager
    {       
        public SchoolResourceManager (IStringLocalizerFactory factory)
        {
            Localizer = factory.Create(typeof(SchoolResource));
        }
        public IStringLocalizer Localizer { get; }
    }

 public class ArtSchoolResourceManager : IResourceManager
    {       
        public ArtSchoolResourceManager(IStringLocalizerFactory factory)
        {
            Localizer = factory.Create(typeof(ArtSchoolResource));
        }
        public IStringLocalizer Localizer { get; }
    }

{
  "ConnectionStrings": {
    "str": "..."
  },
  "Type": "ArtSchool" 
}

 public void ConfigureServices(IServiceCollection services)
{
            services.AddLocalization();
            services.AddSingleton<SchoolResourceManager>();
            services.AddSingleton<ArtSchoolResourceManager>();
            services.AddSingleton<IResourceManager>(cnf =>
            {
                var type = Configuration.GetSection("Type").Value;
                if (type == "ArtSchool")
                    return cnf.GetServices<ArtSchoolResourceManager>().FirstOrDefault();
                    

                return cnf.GetServices<SchoolResourceManager>().FirstOrDefault();
            });
}

@inject IResourceManager ResourceManager

<h2>@ResourceManager.Localizer["Student"] : </h2>

 public class TestController : Controller
    {        
        private readonly IResourceManager _resourceManager;
       
        public TestController (IResourceManager resourceManager)
        {
             _resourceManager = resourceManager;
        }
}