Is it possible to safely mine bitcoin at 13.5 TH/s with hardware with 10.5 TH/s? I want to mine bitcoins, and I have heard that it is possible to overclock an Antminer T9. It said "maximum +200M recommended" for the overclocking. This miner runs at 10.5 TH/s and I would like to make it run at the hashrate of a more expensive miner (the S9), albeit with higher electricity usage. I am curious about bitcoin mining because of the interesting quirks of the SHA256 hash algorithm and how I get to be paid by helping discover hashes with 18+ zeroes (as of writing).

The link for info is at: https://www.infofuge.com/question/how-to-overclock-antminer-t9-to-increase-my-profits/

Note: if there is a higher safe limit, say, 15 TH/s, I would like you to specify it.
You’re not going to get any solid answers for what is safe and possible. Mining hardware varies a lot in what the chips can actually perform at reliably, even between individual units of the same model. 

Overclocking mining hardware in general is a fools errand, there’s a non linear relationship between the frequency and power usage. That is, by adding 20% more power you’re not going to get 20% more performance out, the efficiency is significantly degraded. When overclocking hardware runs out of specification for the cabling and voltage conversion, which significantly increases the risk of fire and damage.