Dowman made his Premier League debut against Leeds United, becoming Arsenal's second-youngest player ever, and has since played three times for the first team.
Nwaneri, who became the youngest player in Premier League history at 15 years and 181 days old, and Lewis-Skelly are two other young stars who have impressed Rice with their growth and confidence.
Rice has been impressed by the trio's ability to quickly settle into the first team, despite being teenagers fresh from school.
"Ethan and Myles have grown significantly as people from last year to this year," Rice said. "They're more confident and outgoing, and that's what you want to see in young players."
Rice was also blown away by Dowman's comfort level in the first team, saying he's never seen a 15-year-old as confident as him.
"Max is just 15, and it's incredible to see how comfortable he is around the first team," Rice said. "He's just a kid, and it's amazing to see him thriving."
Rice has praised the support network at the club, saying it's incredible and allows young players to grow and develop quickly.
"The academy here is impressive, and I've seen how hard the coaches work to develop young players," Rice said.