Hi A S!
Yes, the sentence “He said it would be better if they came later” is correct. Here’s why:
“He said…” is reported speech, and introduces the next clause, “it would be better if they came later.”
“It would be better if they came later” uses the second conditional correctly because it expresses a hypothetical situation in the future. It correctly follows the base structure, “would + base verb, if + past simple.”
The phrase is used to report someone else expressing a hypothetical idea.
Keep up the great work! 💫