No, he did not.

It doesn't really make sense that he would want to. The ideal city of the Republic, at the helm of which is a philosopher-ruler, exists only hypothetically and was not designed to actually exist in real life. Specifically, Plato introduces the ideal city in order to make an analogy with the soul in order to discover the ideal condition of the soul. In other words, the philosopher-ruler governs the ideal city analogously to way that reason governs the ideal soul.

Here is an excerpt from the Republic (book 5) that shows Plato's characters reflecting on whether the ideal city-state that they have discussed is realistic:

The more appeals of this sort which you make, he said, the more determined are we that you shall tell us how such a State is possible: speak out and at once.

Let me begin by reminding you that we found our way hither in the search after justice and injustice.

True, he replied; but what of that?

I was only going to ask whether, if we have discovered them, we are to require that the just man should in nothing fail of absolute justice; or may we be satisfied with an approximation, and the attainment in him of a higher degree of justice than is to be found in other men?

The approximation will be enough.

We are enquiring into the nature of absolute justice and into the character of the perfectly just, and into injustice and the perfectly unjust, that we might have an ideal. We were to look at these in order that we might judge of our own happiness and unhappiness according to the standard which they exhibited and the degree in which we resembled them, but not with any view of showing that they could exist in fact.

True, he said.

Would a painter be any the worse because, after having delineated with consummate art an ideal of a perfectly beautiful man, he was unable to show that any such man could ever have existed?

He would be none the worse.

Well, and were we not creating an ideal of a perfect State?

To be sure.

And is our theory a worse theory because we are unable to prove the possibility of a city being ordered in the manner described?

Surely not, he replied.

That is the truth, I said.

Furthermore, Plato in the Statesman distinguishes between the philosopher and the ruler, which he now calls a statesman. That these are not the same people indicates that Plato doesn't really think that philosophers are meant to be rulers.

The Laws is meant to describe a more realistic political arrangement and similarly features no philosopher-ruler. The city in the Laws is not even an autocracy but is governed by a large council of people.

Plato's interest in political philosophy in the Statesman and Laws reveals that he was profoundly interested in political goings-on, but it doesn't make sense philosophically for him to have pursued the life of a philosopher-ruler.

That being said, it must be acknowledged that on three separate occasions, Plato intervened in Syracuse, usually in conjunction with his friend and colleague at the Academy, Dion. Dion himself was involved in the political scene in Syracuse, and Plato seemed eager to help him navigate political challenges faced by Dionysius, the ruler, and his successor (who ruled on Plato's second and third visits to Syracuse), Dionysius II.

We don't exactly know what happened or what Plato was trying to do. We know that on the first occasion, Plato was banished from Syracuse by Dionysius. There are some stories, perhaps apocryphal, that Dionysius sold Plato into slavery, and his friends had to pay for his freedom from the slavers.

I invite you to read a very well-researched (but speculative) version of the second and third visits to Syracuse in Mary Renault's The Mask of Apollo.

We know only what ultimately transpired: Dion and Dionysius II fought for control of Syracuse, and Plato was dragged into the violent disagreement.

What actually led to Plato's banishment from Syracuse (before ultimately being allowed in again by Dionysius II)? Well, we know that Dionysius clearly thought Plato and Dion were plotting something. And we know that Dion did end up fighting with the ruler's successor over control.

Some legends have it that Plato was trying to turn Syracuse into the ideal state from the Republic. Could Plato have been wanting to make himself a philosopher-ruler? Or maybe he was trying to turn Dion into one? Maybe, if he had his way, he was trying to turn Dionysius II into a philosopher-ruler on his second and third visits?

Some of the totally apocryphal and fake letters that we have from antiquity suggest that the goal was ultimately to turn Syracuse into the ideal city, with a philosopher-ruler at the helm.

But I've already made it clear above that, on philosophical grounds, this just wouldn't make sense. The letters probably say this only because it sounds dramatic and interesting; maybe the writers don't even have a good grasp of Plato's philosophy.

It is much more likely that Plato was hoping to instill some love of the rule of law, defended in the Statesman and Laws, into the rulers there. It could well have been that he wanted to make Dionysius II into more of a philosopher. But a philosopher-ruler? That just doesn't fit with Plato's philosophy. A very specific kind of training regime is required, and Plato couldn't just invent that on the spot for Dionysius II. The ideal ruler exists only hypothetically, unless one day God decided to intervene and set that up for us!