As of February 2021, when typing text into a field with font size set to Auto, the text does not show to the signer as having autosized itself. It appears as the same size, but if there is more text than will fit in the space of the field, an ellipsis appears at the end and the text shows as cut off. It does appear autosized correctly when the final document is created (after all parties have signed). But users consistently report back a problem when they see that the text appears that it will be cut off in the final legal document. In some cases the field is a critical one like business name or loan amount. When they see that the text appears cut off, they assume it will be cut off in the final and that the contract will not be legally binding, and they stop filling out the form and report the problem. This happens so often that it's become part of my job to test it and tell them that it will show up right only once the document is completed by all parties. Please just make the text show up as autosized font while filling out the form (as it does in Acrobat fillable PDFs).