I’m not sure that I understand your question. To train LSTM model you should pass multiple samples where each sample has the shape n_previous_timesteps x n_features.
In the base case the model predicts one next value for each of the samples.
To preprocess the data you can use tf.keras.preprocessing.sequence.TimeseriesGenerator
You pass tabular input data as the first argument and corresponding next values as the second argument. And define length, which in this case should be 80.