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This sounds, of course, like a homework question. And it's tradition here to put the most effort into students who show their work or explain their thinking.
I would use a self-resetting Timer instruction whose Done output added 1 to a counter every time it completed a cycle.
The value of the counter would then be compared to a constant (1,2,3,4,5,6) on a rung that controls the motor starter.
Additional aspects you might want to think of:
1. What starts the sequence: a pushbutton, or an HMI, or an event in the PLC ?
2. Can the sequence be stopped before it completes ?
3. Should you confirm that each motor has started, and not proceed with the sequence if one stalls or fails to start ?
4. Should the operator be able to stop the sequence in the middle ? Should all the motors stop if the sequence is stopped, or should just the ones that have already started keep running ?
5. If the sequence is stopped, what happens when you start the sequence again ?
Something that sounds very simple in theory can get much more complex when you consider all the possible failure, interruption, and restart modes.
Again, welcome to the PLCTalk community !