I would keep in mind .. simple progression in the sense of how a said skill can be used in a society where brut force tends to regain supreme.. like people in the world using wood magic to facilitate the growth of food .. but mc will use multiple magic like eath to mend ground, life to tend the plant, water to nourish the plant in the same way it would but as mana infused it would work better, and simple mana to facilitate growth as whole not just using wood magic to pump up the plant .. with it his own growth as he would come to a world with mana and such, how he would navigate new parents, new values in life, how being a powerful person feel like instead a one with no power .. how to stand up for his values .. sutch ..
Okay, so I feel like you have a few conflicts and angles here already:
1. How he stands up for his values sounds like something he has to get used to?
2. How he relates to the values he's familiar with and has held vs his parent's values and the values of this world.
3. How he relates to his new parents-- what do they think of his new way of agriculture?
As
@LunaSoltaer said, from a literary perspective, any amount of OPness is fine, as long as it doesn't negate the central conflict.
So I'd say he can be ridiculously OP at both agriculture and combat if the story is actually about him learning what his values are now, how to stand up for them, what having power means and how to handle it responsibly, and how to get along with people.
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The sort of questions this brings up for me would be:
How his new way of agricultural disrupts the current economic and thus social system. Can other people replicate his style of agriculture less effectively? There's been people using wood magic to grow food, and now he's basically replacing them, either temporarily or permanently. Some people might be upset about this, he might hold back his full power so he doesn't disrupt the food economy too much, he might want to figure out how to shift people to being part of his process or new jobs for them, etc. How does he deal with this?
By destabilizing how food is made, which is one of the core pillars of society, he might also disrupt the entire society from top to bottom-- how does he deal with this?
People seeing him as a rising new power might try to align themselves with him, possibly in ways he doesn't want, maybe some people start to see him as a god or a prophesized ruler and/or want to try to emulate his stle of agriculture, and try to become his followers. Does he accept them and try to guide them, try to drive them off, or...?
Now, being OP in ways that revolutionize agriculture doesn't make any of these things easier, in fact, the more he uses his powers to be wildly OP at farming, rather, the more disruption he's causing and the more problems he has to deal with. Being OP at combat doesn't make any of these things easier, either-- people might try to kill him at first, and it'd help with him winning the fight, but winning the fight in itself wouldn't help with the discontent or the way he's clashing with current society. Unless he decides to take over the society, of course, and then he has a whole new bunch of fun problems you can throw at him.
...but that's just how I'd go about it, there's other angles you could work with that premise.