Hi there 
You should find the bucket size, and request limits in the following documentation for each plan.
| API | Rate-limiting method | Standard limit | Advanced Shopify limit | Shopify Plus limit | Commerce Components by Shopify limit |
|---|---|---|---|---|---|
| Admin API (GraphQL) | Calculated query cost | 50 points/second | 100 points/second | 500 points/second | None |
| Admin API (REST) | Request-based limit | 2 requests/second | 4 requests/second | 20 requests/second | None |
| Storefront API | None | None | None | None | None |
| Payments Apps API (GraphQL) | Calculated query cost | 910 points/second | 910 points/second | 1820 points/second | None |