Is it possible to transfer ownership of Frontier Outposts in Stellaris using console commands

You occupy the planet, you do not control it, this works similar to EU4.

The occupation grants a large amount of warscore and you can send your armies away, Your opponent has to reinvade to liberate the planet.

Whether you get the planet in the end depends on the war goals, the occupation merely provides additional warscore, with which you can press your demands.

Most importantly though, it prevents the enemy from using the planet and getting resources from it without you having to constantly bombard it and requiring an invasion from your opponent to liberate it.

There are a number of technologies you can research that increase the size of the borders around your outposts and colony ships, including

• Galactic Ambitions

• Manifest Destiny

• Propaganda Transmissions (Repeatable)

The Stellaris Wiki entry on borders also says that:

Border spread appears to work volumetrically. That is, as the empire becomes more dense and grows, its borders also appear to spill outward. Removing colonies or frontier outposts from within the empire's well-established borders may affect the outer border unpredictably.

So building additional colonies and outposts in your empire's interior can increase your borders at the fringes.

If you're expanding your empire via frontier outposts, it's worth noting that

Outposts controlled by sectors do not cost Influence to maintain.