Deck tree - This golden maple makes a beautiful potted tree in this tall terra cotta. Maybe a Princeton Gold Maple "Acer platanoides" or a Golden Full Moon Maple "Acer shirasawanum 'Aureum'" (small, shade)
In my yard: Cottinus coggygria ‘Royal Purple’ . considered a tree but I grow it as a shrub, whacking it back to the ground each spring to keep the height lower and make it bush out. easily grows tall in a season. glows purple with the sun behind it.
Layout scheme for a small garden, i.e. a long and narrow townhouse garden with raised beds adding structure and small trees adding a sense of height