@Arnab Dey Thanks for reaching out. For APIM it is the
Capacity. Capacity is the most important Azure Monitor metric for making informed decisions whether to scale an API Management instance to accommodate more load.
Capacity is an indicator of load on an API Management instance. It reflects resources usage (CPU, memory) and network queue lengths. You will not find any metrics for CPU and memory Utilization in APIM rather than it would be
Feel free to get back to me if you have any queries or concerns.