Step 1 - Either click + drag with your mouse over the items you want to select, or hold down the Command/Control key while you click on each item. You’ll see each one become highlighted, with a blue dashed box around all of the items you’ve selected.
Step 2 - To resize these items as a group, click and drag the blue circles around your group to make them smaller or larger. You can also use the taller blue circle at the top of the group to rotate these items all at once.
When rotating your group selection, hold the shift key to lock your items to a specific degree.