If you want to know, read the Manga

@Alpha Mercenary I have read the manga (1080) and found nothing that confirms that he has the CoC.

Then you missed the last panel

Also common sense tells you that if Garp could rival Roger who is shown to have incredible haki including ACOC, then Garp must have it too.

@ASimon24

I didn't miss the last panel the black lightning in the attack to me indicated only that he used CoA (attacks with CoA also have black lightning) and maybe CoC, but it wasn't a certainty, at least to me.

Being Roger's rival doesn't confirm him as a CoC user.

That said, I did some research and found something that confirms to ME that he has CoC and it isn't the last panel but the penultimate panel, in this panel there is an onomatopoeia present only in CoC imbued attacks.

Not even when a CoA-only attack releases black lightning the onomatopoeia appears, showing that I was wrong in saying that chapter 1080 doesn't confirm Garp as a CoC user.

@Kayky 1104 It's most likely Garp using conquerors haki, but I can also agree with you sense Jimbe in his fight was Who's Who had a similar lighting effect whenever a character uses advanced CoC. To also add onto your claim, when Garp started using his haki, nobody fodder like got knocked out and when Shanks used advanced CoC against Kidd and his crew, most of the fodder that was on KIdd's crew got knocked out.

What townhall is garp

Why is sengoku up there

Because he is a confirmed Conqueror's user

Galaxy Impact shows conquerors projection and black lightning. Also brain users can figure out that you can’t rival Roger without Conquerors.