Import jpg collection and convert to png

I am in the process of importing my personal photo collection (going back 70 years, 250g) into digikam. I plan to use the batch uploader to move the images to the digikam collection including the offered tool to convert jpg files to png files.

Png files can have a greater color depth than jpg. There is a tool in digikam to convert 8 bit to 16 bit. My question is whether I should convert the color depth to 16 bit at the same time. Does it make any difference for existing image files or only new ones brought in?

Maybe the convert to png tool does all I need? Or should I do color depth conversion too?