"I would like to use different expressions to say that." It's not necessary. The phrase "you're right" is ALWAYS good. I do not think non-native speakers should deliberately try to add idioms or colloquialisms, but if you enjoy knowing about them...
[Nod and not say anything]
[Not and grunt "Uh-huh."]
"Yes."
"Indeed."
"I see."
"I get it."
"That's true."
"That's so."
"Isn't that true!" (Rarely: "Ain't that the truth?")
"Isn't that so!" (Rarely: "Ain't that so!")
"You bet."
"I agree."
"You said it."
"I couldn't agree more."
These might be regional, or dated, or simply colorful expressions of individual personality--but these are common:
"You hit the nail on the head."
"You can say that again."
"Well said."
"Amen, brother."
"Hear, hear!"
I am not sure if these are in consciously patterned on Spanish, but I've heard both of these expressions used, more than once, by native English speakers who just like the phrases:
"So it is."
"You have the reason."