Hello, I am planning to make assets for a concept game (technically I did start)

One of my large problems is... for a character that is 160x160px what size should the world tiles be to make the character seem a normal size? The game will be in the style of Children of Mana/LoZ

The size of the tiles you're building things out of has no direct impact on the visual size of the objects in the game world. You can build a door out of one tile, 2 tiles, 4, 6, a hundred tiles... You should first create some rough graphics for various visuals you'll need, then decide how you can split them up in a way that's convenient to work with and allows an economical use of tiles (that is, easy reuse).

Another thing to consider is how, if at all, the tile size will impact gameplay. For example, platformers often have their logic tile size (for their coordinate system and collision checking) be the same as the graphical tile size, since the world has to be built out of tiles that size anyway. The character size may be defined in terms of those tiles, but their dimensions are often not 1. Characters are often multiple tiles tall and/or wide.