How can composition, color, and perspective make a photo feel powerful or splendid?

To some extent, as others have noted, "power" and "splendor" do mean different things to different people. But to some extent, we do mean more or less the same thing by them, or we wouldn't mostly use the same words to discuss what we mean.

Here are a few composition tips that can give a sense of power or splendor.

(1) Physical largeness speaks to power, so filling the frame with your subject is better than having it at a distance and small.

(2) Shooting from below, looking up at the subject (a [worm's eye view]1) also implicitly depicts the viewer as lower and perhaps smaller than the subject, conveying a sense of the largeness or highness of the subject.

(3) Strong contrast, as noted above, conjures a sense of dynamism and strength. Vivid colors lend themselves to this, I would believe, although low-key colors wouldn't necessarily be counterproductive. It would depend on the mood you want to create, I would think. A splendid think might also be languid, or old, for instance - and pale colors can convey either of those.

(4) The pose and attitude of the subject are also important. Sprawling on the floor doesn't scream splendor, except maybe a dissipated or languid splendor; likewise, teddy bears are going to be hard pressed to seem powerful or splendid in any circumstance. On the other hand, though, a bride in elegant dress and with grave (but not somber) expression will come across as very splendid or dignified. Shot from a low angle, she could even seem powerful - think of a fairy-tale snow queen. An odd wedding photo, but maybe what you're looking for. I would avoid anything that could be construed as cute or cozy (contrary to powerful) and anything that could be trendy or chic (because these don't speak to the timelessness we feel in the present of much that we usually consider splendor).

Well, those are the thoughts that come to mind for now, thinking of the pictures I've seen or shot of things like big trees, business executives, cathedrals, and the such that we might describe as powerful or splendid.

Hope it helps!