add_option_fields() - Function used to add fields to wp_admin. A good example of usage is in class service-contect-form.php or service-bbpress.php
front_action() - If plugin has forms (for example contact form) you should add a function which injects consent checkbox which allows processing of data. You should add checkbox template to plugin’s hooks.
Do not forget about validation for this field. You can use service-bbpress.php::front_action() as an example.
If plugin stores any user data you should implement following functions:
collect() - collects data stored by plugin
is_forgettable() - must return true
forget() - handle removing data stored for given user
breach_recipients_filter() - usually gets all users whose data is stored by plugin