Bone in is best for curry.
Not in the oven usually....I've never used a jar (not being snooty honest...I just haven't!)
But in my experience of eating jarred currys, they do tend to be bland.
I would buy some curry powder...and add that. Here's what I would do if I had to use a jar.
In a big pan, add about two spoons of oil and on a low heat brown your thighs...just cook them on each side till they're a little bit golden...only takes about 5 minutes.
Remove from pan and put on a plate to one side.
Chop an onion finely...fry it on low heat in the same big pan...with about two tablespoons of oil.
When it's just getting a little bit see through but NOT brown...add your garlic.
For this I would have crushed 3 cloves of garlic...( you could buy a jar of garlic paste and use 3 teaspoons)
Fry for a further minute or two on low heat.
Now put the thighs in and then add your jar of sauce plus a spoon of curry powder.
If the sauce isn't covering the thighs...put a lid on the whole thing and simmer, stirring it now and then.
Turn the thighs over after about 10 minutes.
That's an easy way of making a jar a bit more interesting.
Serve with rice and some fresh coriander on top.