Is there any native Mac OS X 10.15.3 keyboard layout that contains all ASCII characters plus č, ç, è, ǩ, ò, š, and ž?
ABC Extended can make all those and more I think.
https://sites.psu.edu/symbolcodes/mac/codemacext/
but it's easy to make a custom layout with whatever you want using
https://software.sil.org/ukelele/