Hi Jessy.
Apple's trade-in programme does not accept current-models. As such, until your iPad is superseded, trade-in won't be an option. When trade-in does become an option, the potential value will be significantly less than you paid.
As such, selling your unwanted iPad privately will likely be the only way to recover a significant proportion of the purchase cost - which you can put towards the purchase of a different iPad model.
You can verify eligibility for trade-in and, where applicable, obtain an estimate of the potential trade-in value here:
Apple Trade In - Apple
Be aware that trade-in values are always considerably lower than the original purchase price. For devices purchased directly from Apple, in most countries/regions you have up to 14-days to unconditionally return an unwanted item for exchange or refund - this providing opportunity to exchange a device for an alternative, with greater internal storage, for just the cost difference. This opportunity lasts for only 14-days.