58 cards where the card types include “dragon” and the mana value < 5 and the color identity ≤ RU

A-Dragonborn Looter (Alchemy Horizons: Baldur's Gate #A-117)
A-Pseudodragon Familiar (Alchemy Horizons: Baldur's Gate #A-128)
Arcbound Whelp (Modern Horizons 2 #113)
Archwing Dragon (Avacyn Restored #126)
Atsushi, the Blazing Sky (Kamigawa: Neon Dynasty #134)
Avaricious Dragon (Magic Origins #131)
A-Young Red Dragon // A-Bathe in Gold (Alchemy Horizons: Baldur's Gate #A-197)
Bhaal's Invoker (Commander Legends: Battle for Baldur's Gate #163)
Chaos Dragon (Commander Legends: Battle for Baldur's Gate #784)
Dragonborn Immolator (Alchemy Horizons: Baldur's Gate #51)
Dragonborn Looter (Commander Legends: Battle for Baldur's Gate #65)
Dragon Egg (Commander Legends #173)
Dragon Hatchling (Jumpstart #310)
Dragon Turtle (Adventures in the Forgotten Realms #56)
Dragon Whelp (Dominaria Remastered #116)
Fearsome Whelp (Alchemy: Innistrad #40)
Firespitter Whelp (Foundations #197)
Fledgling Dragon (Modern Horizons 3 #280)
Furnace Whelp (Jumpstart #323)
Gadrak, the Crown-Scourge (Core Set 2021 #146)
Galazeth Prismari (Strixhaven: School of Mages #189)
Invasion of Tarkir // Defiant Thundermaw (March of the Machine #149)
Invasion of Tarkir // Defiant Thundermaw (March of the Machine #149)
Jaded Sell-Sword (Adventures in the Forgotten Realms #152)
Leyline Tyrant (Zendikar Rising #147)
Lightning Dragon (Vintage Masters #177)
Livaan, Cultist of Tiamat (Commander Legends: Battle for Baldur's Gate #188)
Loch Dragon (Throne of Eldraine #211)
Manaform Hellkite (Innistrad: Crimson Vow #170)
Moonveil Regent (Innistrad: Midnight Hunt #149)
Nalathni Dragon (Mystery Booster 2 #197)
Nimbleclaw Adept (Commander Legends: Battle for Baldur's Gate #86)
Oculus Whelp (March of the Machine #69)
Opportunistic Dragon (Forgotten Realms Commander #134)
Patron of the Arts (Commander Legends: Battle for Baldur's Gate #191)
Phantasmal Dragon (Duel Decks: Jace vs. Vraska #14)
Phyrexian Dragon Engine (The Brothers' War #163a)
Pseudodragon Familiar (Commander Legends: Battle for Baldur's Gate #88)
Rakdos Pit Dragon (Ravnica Remastered #120)
Rathi Dragon (Tempest Remastered #150)
Reckless Barbarian (Commander Legends: Battle for Baldur's Gate #193)
Renari, Merchant of Marvels (Commander Legends: Battle for Baldur's Gate #90)
Sarkhan's Whelp (Core Set 2019 #299)
Scion of Shiv (Jumpstart: Historic Horizons #24)
Shivan Devastator (Dominaria United #143)
Skyship Stalker (Forgotten Realms Commander #141)
Slumbering Dragon (Magic 2013 #148)
Smoldering Egg // Ashmouth Dragon (Innistrad: Midnight Hunt #159)
Smoldering Egg // Ashmouth Dragon (Innistrad: Midnight Hunt #159)
Sprite Dragon (Commander Legends: Battle for Baldur's Gate #852)
Stingerback Terror (Outlaws of Thunder Junction #147)
Stirring Bard (Commander Legends: Battle for Baldur's Gate #195)
Swashbuckler Extraordinaire (Commander Legends: Battle for Baldur's Gate #198)
Territorial Hellkite (Commander Legends: Battle for Baldur's Gate #809)
Thriving Skyclaw (Modern Horizons 3 #141)
Thunderbreak Regent (Forgotten Realms Commander #147)
Town-Razer Tyrant (Alchemy: Innistrad #45)
Vengeful Ancestor (Murders at Karlov Manor Commander #163)
Verix Bladewing (Dominaria #149)
Young Red Dragon // Bathe in Gold (Commander Legends: Battle for Baldur's Gate #210)

Though this query has ended, its relics still slumber in New Argive.