With v18 of the Google Ads API, you can now use the Recommendations.GenerateRecommendations 
When using the GenerateRecommendations method with a recommendation type of CAMPAIGN_BUDGET impact metrics  to help understand the effect that implementing the recommendation will have on account performance.
Explore additional Recommendations API features 
Recommendations in the Google Ads API offer several ways to increase your campaigns' performance through customized suggestions like adding new keywords or updating your bidding strategy. With RecommendationSubscriptionService, you can subscribe to automatically apply specific recommendation types of your choosing for your account. To retrieve and process recommendations directly, you can leverage the recommendation 
To explore the full recommendations offering, check out our implementation guide .