Hi Sunil,
Thanks for reaching out. With regards to your concern about to pass goal details using API, there is no way to set the goal using the API. You will have to do it manually in the UI. You can use goals choice in the UI is to help guide through the campaign creation process by adding/removing relevant options. However, if you are interesting in monitoring specific goals, you can use the CampaigGroupservices and for checking the campaign group performance target use the typeCampaignGroupPerformanceTarget field. Please refer to this guide.
Let me know if you have any questions.
Thanks,
Nirmita Patel Google Ads Team