Use below steps to adjust the button size:
In MC open POS Customization-->Layouts-->Select Layout(Edit)-->POS Designer
--In the Customization Window, click on Customization
-- In the customization tree drag the "blank" on the preview, between the "TransactionGrid" and "TabbedControlGroup1"
-- Right-click on "TransactionGrid" and select "size constraint" > "Lock size"
-- Now select the empty space from the design and drag it back to the "customization window"
-- In the background, you can see the "TabbedControlGroup1" area is extended
--Click on OK to save the changes
Ticket Reference: #14581