Hi @vmlr1098, welcome to the Streamlit community!! 
Streamlit provides four different ways to set configuration options, and setting them as flags on the command line when running streamlit run is one of them.
When deploying your app, you’ll want to set the maxUploadSize config option in a .streamlit/config.toml file uploaded to your GitHub repo containing the following:
[server]
maxUploadSize = 400
Once you create the .streamlit/config file with the above contents, the upload limit of st.file_uploader per file should be set to 400 MB.
Happy Streamlit-ing! 
Snehan