Hi Srikanth,
What you want is to show contacts and leads in the same grid, right?
If so, contact entity and lead is 1:N relationship, you can use Nested grid view of OOB ‘Editable grid’ control to achieve it.
1.Sub-grid in third entity(example:Account).
Navigate to Settings > Customizations > Customize the System > Entities > Account > Forms to open one form.
Double-click contact sub-grid to open dialog, and then add control.

Test Result:

2.Main grid.
Navigate to Settings > Customizations > Customize the System > Entities > Contact.
Move to 'Control' tab to add 'Editable Grid' and fill information as following screenshot shown.

Test Result:

Regards,
Leah Ju
Please mark as verified if the answer is helpful. Welcome to join hot discussions in Dynamics 365 Forums.