This page exists for load testing. It is plain text with no images, scripts, fonts, or theme styles, so each request transfers only a few hundred bytes after compression.
It is still a real WordPress page. WordPress renders it once, then the server keeps the finished HTML in RAM and serves every later request straight from memory without running PHP or touching the database.
The full homepage is about 25 KB compressed. At that size the server network card limits throughput to roughly 2,500 requests per second. This page is under 1 KB compressed, about 35 times smaller, so the network stops being the bottleneck and the test measures how many requests the server itself can answer.
Edit this text in the WordPress editor like any other page.