As per Cambridge dictionary and others, the word 'deck' in its verb form means to decorate or add something to something to make an effect: https://dictionary.cambridge.org/us/dictionary/english/deck
However, I see two ways of using the verb in practice: deck with and deck out in
When I went through the examples quoted on most of the dictionary sites, I came to an understanding that, "decked with" is generally used to refer to objects, places or things — The room is decked with flowers.
Where as, "decked out in" is used when we refer to people and their clothes — The guests were decked out in fancy clothes.
I have not found examples where they are interchangeably used except the usage of decked in used with people in bible-related old texts — decked thee with ornaments.
https://biblehub.com/ezekiel/16-11.htm
I am not sure if my understanding is correct.
Questions:
#1 Can "decked with" be used to explain someone wearing jewels on them? for ex: She was decked with brilliant jewels.
#2 Can "decked out in" be used to explain a non-living thing like a room or place? for ex: The room was decked out in flowers.