Consistency groups- Protection domain

Yes. The manual screenshot will only create one screenshot. If you configure a schedule it will create snapshots on the given time. 

I have schedule with 3 consistency groups but only one snapshot triggered.

it should create 3 snapshots rights?

it should be one only , however when you click restore you have option to select each single one 

Is there any article how multiple consistency groups works snapshot works.

Just want to why multiple consistency groups need to create and how it works in replication snapshots

I will trigger one snapshot task, however, each VM will has its own recovery points

Then why do we need to create multiple consistency groups, as per Nutanix we need to limit the consistency groups as small as

You don't need to create consistency groups, it is not mandatory. It is to group virtual machines which depend on each other (for example webservers and databases). 

If you create a protection domain then select the vm's and add then. The consistency group is not mandatory in the step. 

If you do want to create a consistency group keep them as small as possible. And then, when a snapshot is trigger manually/scheduled, each machine will get a snapshot at the same time. 

however we have multiple consistency groups, it will trigger one snapshot for all the consistency groups in protection based on the schedule is it right

Yes. But offcourse the “one snapshot” is per machine. It is not 1 snapshot which include all the machines in the consistency group. You will see 1 snapshot in the data protection dashboard.

But if you click on restore you can choose individual virtual machines (or multiple/all). 

I have 3 consistency groups, one have 5 vms,9vms, 8vms . for all 3 consistency groups one snapshot created in schedule. My assumption is one snapshot for consistency group. Is there any reference article that will explain about multiple snapshots

I'm sorry. But I really dont get the question. (sorry for that). 

What is the exact issue? 

If you have 3 CG in 1 Protection Domain. The snapshots for each CG will be at the same time. 

for me only one  scheduled snapshot created for 3 cgs and it contains all 22 machines, is there any thing missing in configuration to get each consistency group one snapshot, aos version 6.5.3.5

yes, only concern is even though we have multiple consistency group it will create one snapshot it will contain all the vms and cg is it normal or not

Yes correct. (But you can still restore individual vm's if needed ;))