6:3 And when He broke the second seal, I heard the second living creature saying, "Come."
And when He broke the second seal,
Since the breaking of the seals are listed individually, this indicates that these seals are a series of events to take place on the earth. It's the only place where time really has any meaning; in heaven, time is forever and ever --- (Revelation 4:9).
I heard the second living creature saying, "Come."
It is not clear if this second creature is the same as the second one described with a calf's face (Revelation 4:7). If there is a connection between the demeanor (calf/ox/servantry} and the red horse (war and bloodshed), it cannot be made with any conviction. When peace is taken, war abounds, and war certainly makes servants of those remain alive. The dead in a war don't care.