Product with the custom option available Out of the box in Magento 2. You can add, delete or update custom option of a product using an admin panel or creating a script by programmatically.
You can check the relation for each custom option table with another table in Magento 2.3
catalog_product_option is the primary table to manage Custom Option related data for a product.
catalog_product_option
— add an entry for each type of custom option like dropdown, radio, text field etc…
catalog_product_option_type_value
— add each type separate value with option_id from a catalog_product_option table and manage sort order of option and separate SKU of each item option
catalog_product_option_title
— Store the title of Option Main title
catalog_product_option_type_title
— store the subtitle of each option specific to store id
catalog_product_option_price
— add each option price for field value except dropdown, radio,multi-select, and checkbox if the option has assigned extra price with respect to catalog_product_option’s option_id and store id value with an input type field
catalog_product_option_type_price
— add the price of the dropdown, radio,multi-select and check box option to the above table