You can train a multi-output LSTM network using a custom training loop. Here is an example of how to train a network with multiple outputs: https://www.mathworks.com/help/deeplearning/ug/train-network-with-multiple-outputs.html
You may also find this doc page helpful: https://www.mathworks.com/help/deeplearning/ug/multiple-input-and-multiple-output-networks.html.