These are two suggestions for very long or complex forms which may require more time and effort from the user to fill in.
The user could save their progress and return to the form at a later time and continue where they left off.
Multi-step forms would allow you to break a form up into ‘pages’ to make longer forms more bit-sized. Ideally there would be a progress indicator with the users progress in percentages and/or the steps listed in a timeline of sorts, like “step 1 - personal details”, “step 2 - application details”, etc.