Domain expansion is the ultimate technique that any Jujutsu sorcerer can use in Jujutsu Kaisen. This technique is believed to be the pinnacle of Jujutsu Sorcery and that is precisely why only a handful of characters have shown the ability to utilize it so far.
Domain Expansions require the user to have an Innate Technique which they can then infuse within their Innate Domains to create powerful Domain Expansions. So far, only a handful of characters have unlocked this ability, however, there are many in Jujutsu Kaisen who can, perhaps, unlock this ability in the future.
5 Yuji Itadori
Yuji Itadori is the protagonist of Jujutsu Kaisen and, as such, it shouldn't be a surprise to the fans to see him as one of the characters who can utilize Domain Expansion in the future. While Yuji doesn't have an Innate Technique, he can, perhaps, develop one in the future, even though it is believed that most Innate Techniques are formed by the age of 5 or 6.
Yuji could simply be an anomaly. At the same time, Gojo has hinted in the past that Yuji might be able to use the Cursed Techniques of Sukuna in the future. Fans might be able to see him utilize Malevolent Shrine even though Sukuna is not in his body anymore, or, perhaps, he will develop his own Innate Technique and utilize them in the future of the story. Either way, fans should not count out Yuji as a Domain Expansion user just yet.
4 Aoi Todo
Aoi Todo is certainly one of the most skilled Jujutsu Sorcerers in Jujutsu Kaisen. He is also a great fighter and possesses an incredible understanding of Cursed Energy in general. Todo certainly does possess an Innate Technique called Boogie Woogie and this power allows him to swap places with anyone and anything with a clap of his hands.
In the fight against Mahito, Todo lost the ability to use Boogie Woogie, since he ended up losing his arm, however, if this technique can be activated using a prosthetic or even another person's arm, then there is a chance for Todo to gain a Domain Expansion. Given his understanding of Cursed Energy, fans shouldn't be surprised if, at some point, Todo develops the power to use Domain Expansion.
3 Kirara
Kirara is one of the most impressive people in Jujutsu High and the third year student at this point in time. They are quite a skilled fighter and their understanding of Cursed Energy is quite good, having studied it extensively for 3 years. They also possess a powerful Innate Technique called Love Rendezvous and having an Innate Cursed Technique means that they do have the potential to tap into Domain Expansion later on in the series.
Given that their skill is immense, fans shouldn't be surprised if Kirara would, at some point, tap into the power of Domain Expansion.
2 Nobara
Nobara is a character who has not appeared in the manga for quite a long time and that is down to the fact that she's presumed to be dead. However, as is the case with Shonen series, fans can never be too sure about character deaths, especially when it comes to important characters like Nobara.
Nobara possesses incredible skill up her sleeve and her understanding of Cursed Energy is immense as well. Like Yuji, she also possesses an Innate Technique called Straw Doll Technique. If Nobara does return and knows how to use a Domain, she can then, later on, learn to infuse her Innate Cursed Technique into the Domain and create a Domain Expansion. Given how skilled she is, Nobara's domain expansion could be extremely dangerous and pose a threat to even the strongest characters in the entire story. Of course, all of this hinges on her being alive, which fans have no confirmation for just yet. In fact, the story is already in its ending phase, and with each passing chapter, hopes for her return fade away more.
1 Mei Mei
Mei Mei is a great Jujutsu Sorcerer who has not played a great role in the series so far. She is quite a skilled user of Cursed Energy and also possesses an Innate Technique called Black Bird Manipulation, which allows her to imbue crows with Cursed Energy and utilize them in combat. Given her high levels of Cursed Energy and a decent understanding of things such as Domains, Mei Mei could, in theory, learn how to use a Domain Expansion. Attaining a Grade One Jujutsu Sorcerer rank is proof that she's quite skilled with the usage of cursed energy.
While it is unlikely for her to be given that much focus in the story, given the handling of the female characters in Jujutsu Kaisen, Mei Mei should be able to learn a Domain Expansion. Whether fans will get to see it in the future or not is up for debate.