По центру по горизонтали

Horizontally centers the selected objects. If only one object is selected in Draw or Impress, the center of the object is aligned to the horizontal center of the page.

Доступ к этой команде

Choose Format - Align - Centered (LibreOffice Writer, LibreOffice Calc).

Choose Shape - Align - Centered (objects selected) (LibreOffice Draw).

On Align bar (LibreOffice Impress, LibreOffice Draw), click

По центру

Положение выбранных объектов по вертикали не влияет на эту команду.To align the individual objects in a group, to enter the group, select the objects, right-click, and then choose an alignment option.