Can I trade in MacBook for an iPad?

Yes. In general, you can trade-in a Mac against purchase of a new iPad - or other Apple device.

You can verify eligibility for trade-in and obtain an estimate of the potential trade-in value here:

Apple Trade In - Apple

You should be able to trade-in eligible devices both online, or at a physical Apple Store - many choosing the latter option by preference as the device can be checked, the trade-in value finalised and the process completed while in-store. Be aware that Apple’s in-store trade-in values may differ from the on-line estimate.

See the answer in this similar thread:--> Can I use my MacBook Air as a trade in fo… - Apple Community