Unity of style is one of the basic rules of design. It is better to use the same border radius, the same shadow style, etc. on all buttons. Otherwise, the buttons look messy, sloppy and ruin the whole impression of the design.
If there is a caret icon to the right of the button label, it is better to reduce the right padding of the button. This works with vertical icons.
Square, round, and horizontally stretching icons usually don't require optical adjustments.
The destructive action should always be secondary and have less contrast than the primary action. This action does not need to be bright as it increases the risk of mistakes and accidental clicks.
In fact, the destructive button does not even have to be red at all. Delete, cancel is always a secondary action. So it might be a more low-key and quieter button.
The button must be shaped and look like a button. Even if this is a ghost button, it shouldn't really like a ghost.
Sometimes not all actions need to appear as buttons. That's okay. It's just important to try to make a link or button look like a clickable item.