Minecraft wiki entry for Sneaking, associated text: While flying in creative mode, holding the jump and sneak buttons simultaneously causes the player to remain at the same height.
In Bedrock Edition, the player uses a sneaking stance when flying downward. The player can also place blocks on chests, furnaces and other utility blocks in this stance, suggesting the player is actually in a sneaking mode. In Java Edition, the player no longer enters sneak mode when flying downward, but they still don't interact with blocks by right-clicking.
In Bedrock Edition, the player can bridge out by looking at the air block they are placing on, though it must be adjacent to an existing block. This works even if the player is not sneaking.[1]
In Java Edition, the player must travel to the edge of the block (usually by sneaking) and look backward to place the next block.
If the player begins to sneak while sprinting, they sneak faster than someone who sneaks without sprinting.[2]