experimental tnt cannon development base

make a nice looking bridge

bridge (like others suggested) or maybe make a small dam and fill up some of the space behind it with water

Build a navy base and piglin empire planes invading it

Fill it all with TNT and light the top one.

build a nice, stone bridge between the two cliffs

Read my mind. In addition to the bridge, you could build some roads between a small town and a mega base

A house between the river