Conspicuous

1. Everyone is dressed formally except John, who is not. He is also wearing some bizarre, colorful jacket, whereas the other people are wearing plain shirts and suits.
John looked conspicuous at the party.

2. At the same party, Emma looks extraordinarily beautiful with her diamond neckless.
Her beauty and the necklace made her look conspicuous.

3. On Word Reference someone asked a question and 20 people answered it with understandable and simple English but some user used lots of jargons and too much of padding
His answer was conspicuous.

I wouldn't use conspicuous here unless it's meant as criticism, which I don't think it is. I'd say made her stand out, or similar. 👁 Thumbs Up :thumbsup:

Aguas Claras said:

You need to be careful with "conspicuous" because it often has or implies a mildly negative (or sometimes ironic) connotation:
"John was very conspicuous at the wedding because he was wearing a bright pink suit" is a polite way of saying that perhaps he didn't look right for the occasion. However, if your meaning is positive or neutral, you might say "John stood out at the wedding because he looked so elegant."

sound shift said:

It's not necessarily the best choice, even if it's used negatively. I don't think it's particularly suitable for either of your sentences in #6. I might say:

"He drew attention to himself with his weird habit of laughing loudly in theatres."

"He was the only 6'2 guy in the hall; everyone else was under 5'8. He stood out."