This concept is known as a "Single-Biome Planet" and they are a fictional concept.
It is impossible for a planet that orbits a star to have only one biome while remaining anything akin to Earth, however it is possible for a planet to have reduced extremes of temperature compared to Earth.
The thicker a planet's atmosphere, the more heat will be distributed around the planet, so you could have a planet with a warm equator and poles that are only a little cooler.
Additionally, having lower topography would result in rain-bearing air being able to transport moisture further from the sea, so a flatter planet will have reduced continental aridity.
You must be aware though, that if the atmosphere is too thick, it will have consequences for human survival. Likewise, low topography suggests that the planet has either greater surface gravity, or reduced tectonics, both of which have consequences for life. (e.g. reduced carbon cycle)