can I exchange my new iPad to one with more memory?

That would be according to the exchange policy from whomever you bought it. Call them and ask. Apple's policy is that you can return a product in 14 days for whatever reason. Apple may charge a 10 to 15% restocking fee. Be sure to have your receipt.

Apple do not accept trade in. Sell it and buy a new iPad with higher capacity.

Within 14-days of purchase you can return it for refund. Then use that refund to buy what you want. Outside the 14-day window, there is not a refund or exchange.

I believe you can return it if it's within 14 days.