By default Nginx will allow uploading 1 MB file, By using below directive we can upload up to 10 MB If we need to upload larger than 10 MB just replace 10 with your specified size.
client_body_in_file_only clean;
client_body_buffer_size 32K;
client_max_body_size 10M;
Once above directive defined in virtual host restart the Nginx to take effect.