Yes and no. People who know what they're doing will replace failure points proactively - upgrading cooling systems, upgraded connecting rods, stronger wrist pins, etc. I had a car pushing 900+ WHP that had fewer powertrain issues than my buddy's stock 240 BHP truck.

Generally, modding anything beyond the ECM / TCM / PCM will be visible to the service center and claims will be denied.

If you stick to software alone, you're generally not looking at more than maybe 15-50 hp difference in most cars, depending on your starting point (you're getting a small percentage increase, so more powerful cars will see more of an increase).

Most ECM / PCMs do not have adequate tamper protection to detect being modded and then flashed back to stock, which is a common practice in the auto enthusiast world, and leads to people who technically shouldn't be getting repairs under warranty to get them.

Newer ones are getting better at detecting this.