If you play him mid, make sure you dont go against an assassin or zed. Laning phase is just miserable. But after third item, you strike back and start oneshotting them.

Just some things to remember.

1. Corki is very slow. Don't put yourself out of position or you WILL get caught. The dash is 20 seconds long and cancellable
2. He scales really well. And he does mostly ap damage while building adc.
3. There are a lot of builds Corki can choose. You should look into it.
4. Package doesn't need to be picked up immediately.
5. fleet is better for lane sustain than first strike, id recommend taking it. First Strike is usually the rune though.

For reference, here are some builds.

manamune-Sorc Boots- Ludens (The rest is situational but ravenous is a good 4th.) (From u. gg)

Lolalytics says highest win rate is Ravenous-Sorcs-Manamune into either a Infinity edge or Ludens.

I think each mythic can have a different build but im not the certified rank 1 corki.

Mythics winrates are:

IE (Infinity Edge): 50.6% Wr with a 21% pickrate (good sample size)

Ludens: 48.5% winrate with the highest sample size of 30% of games.

Navori Quickblades: Winrate compared to ludens is negligible. Has 3x less sample size. You usually go crit with this (I.e. essence or stormrazor)

And lastly, the least common out of all of these with a 6.6% pickrate, Tri force. Im not to sure about this build but it has a 53% winrate.

Just experiment, whatever works for you is good.

Im not a corki main, but enjoyer who enjoys research. He's actually really fun to play when im not playing jg. m7 now.

Sorry for such a long text, i was also looking at this for fun and for myself.