hi, i was wondering if there was a way to do lantau and macau on a day trip?

I highly recommend ferry between HK and Macau. From Lantau, you can easily reach the nearby Mui Wo Ferry Terminal, where you can take a ferry to Central first. Then go to the HK-Macau Ferry Terminal near Sheung Wan, where you can take the direct ferry to Macau then.

Well, from Macau to Lantau, you can use the same approach.