Hi Yogesh,
Thank you for reaching the support. You could use Ad Performance Report to get the list of the ads associated with a campaign based on the campaign id. Please find below the sample report query for reference.
SELECT Id, CampaignId FROM AD_PERFORMANCE_REPORT WHERE CampaignId IN ["2XXXXXXXX2", "20X26XXXX5"] AND Status IN ["ENABLED"]
Let us know if you need any additional information.
Regards,
Nikisha Patel, Google Ads API Team