The training resolution and inferencing resolution is decided by the model input layer resolution.
The larger the model input resolution, the larger the model size.
DeepStream SDK is only an inferencing framework. Since you have trained the models, you should have known about the model input resolution.
For inferencing with DeepStream SDK, you can use gst-nvinfer to deploy your trained model. The resize, format conversion,… are done inside DeepStream, the only thing you have to do is to fill the configurations with proper parameters. Please refer to DeepStream samples. C/C++ Sample Apps Source Details — DeepStream 6.2 Release documentation
DeepStream SDK FAQ - Intelligent Video Analytics / DeepStream SDK - NVIDIA Developer Forums