Agreeing with AJ's answer for the immediate near future. If Wanda had the power to manipulate an entire town full of people, she can certainly independently do it to one person.
Long term, we can probably perform some Marvel Kremlinology here. In the comics Agatha is known for teaching others magic, and that includes Scarlet Witch (Avengers #128). Of course she's generally portrayed as benevolent in the comics as well, which makes her Wandavision portrayal a bit of a departure.
She was also involved in the eventual creation of Wanda's children. Given that one of them ended up being on the Young Avengers team, and we've already seen appearances by two other members of that team in the MCU (Cassie Lang and Kate Bishop), its quite possible they will reappear in some form eventually.
The Wandavision dialog bits about Wanda needing to learn and Agatha offering to teach her, very strongly implies (via the scriptwriting principle of Chekhov's Gun) that they are planning to have that happen sometime in the future.
So indications are that the current plan is that Agatha will spend at least some time in the future teaching and/or mentoring Wanda in magic. There's also a decent possibility she will end up being involved in the reintroduction of at least one of Wanda's children.