Is it possible to get previous entity data in the same odk form?
For example, Get patient general information from a previous entry in the same form on another day of the visit If possible, please guide.
Are you using the new Entity-based data collection functionality?
When you say "the same form" do you mean within a single submission? You can use variables to reference the value of previously answered questions: https://docs.getodk.org/form-logic/#variables
Or sharing data between submissions on a device? This is only possible on a somewhat limited manner right now. For example, you can pull the default value for a question from the last saved record. This is often the most recently created record but it could also be a previously-existing record that was edited and saved. For the first record ever saved for a form definition, the last saved value for any field will be blank. See the docs: https://docs.getodk.org/form-logic/#values-from-the-last-saved-record