The Inflationary Epoch was from about 10−36 seconds to or so seconds. Notice the duration label change from “era” to “epoch” and from a narrow time to a range. However, also note that we are still within the first millisecond of the Big Bang. This was a period of extremely rapid expansion driven by a speculative field called inflaton. While the universe did not explode into something, it did increase in size by a huge factor. The very fabric of the universe, space itself, increased in size by a factor of at least 1026, smoothing out any irregularities and leading to the uniformity we observe in the cosmic microwave background. The rapid expansion also drastically cooled the universe.
A bit speculative. Supported by indirect empirical evidence from CMB observations, suggesting a rapid early expansion that explains the universe’s large-scale uniformity and structure distribution.