It’d be helpful if the 16x16 were in a different part of the sheet than the 8x8.
Vertically, s4m_ur4i_huge-assetpack-tilemap.png starts with 8x8 palette, then does some 16x16 blocks, then a bunch of 8x8, then more 16x16 blocks. This makes accessing the 16x16 blocks awkward since you can’t slice with a 16x16 grid and need to either edit the png or slice 8x8 and make all your 16x16 objects out of 4 objects.