You get your chat logs if you request your account data from Riot.

Somebody asked this earlier this week.

You also get all of your chat logs, not just the ones that were reported. So some of them are empty, or really short like this one. They're a bit hard to read.

"gameCreationTime" : 1532383038698, "text" : [ { "summonerName" : "disregardable", "chat" : "the wings are cool", "sentTo" : "CHAOS", "gameTime" : 43686000 }, { "summonerName" : "disregardable", "chat" : "glhf team", "sentTo" : "CHAOS", "gameTime" : 50451000 }, { "summonerName" : "disregardable", "chat" : "jinx b", "sentTo" : "CHAOS", "gameTime" : 98210000 } ], "success" : true

but if you want your chat logs, even though they look like that, you can ask for them. If you really want to, you can figure out exactly in what % of your games you're toxic in.

support.riotgames.com

You go the support website, submit a ticket under "I need help with account management, data requests...", then under the "I need help with box" you select "I would like to request my account data". Blitzcrank bot will handle it. You have to wait a month before receiving the data, and if you change your email in that time you won't receive the data, for security purposes.