Is it possible to make two level category selector? So first I select from parent categories and only then the parent’s child categories appear or any other way for example make portfolio galleries page for each parent where the child categories visible only?
Thank you for your question.
To achieve this, you have to develop custom code in the child theme of Jevelin theme.
Developing custom code for custom functionality is beyond the scope of support that we provide here. Please see https://themeforest.net/item/jevelin-multipurpose-premium-responsive-wordpress-theme/14728833/support
If you are not a developer then you can consider hiring a developer to develop it for you. You can hire a developer from any freelance site. Shufflehound recommends the developer https://www.upwork.com/freelancers/~011652ffec8865c6d5