Radisa wants you to research Octillery so she can use its ink as a recipe ingredient.
The Request
Talk to Radisa in Jubilife Village to accept the request.
Research Octillery
Octillery can be found at Islespy Shore in Cobalt Coastlands.
Reward
You will get 5 Bean Cake and 1 Exp. Candy M as a reward for showing Radisa the completed Octillery Pokédex entry.