the fundamentals of mapping hasnt really changed that much over the years. pishifat videos have talked about the core tenets of what makes a map a map generally enough that it can be applied to anything (up to a certain extent)
if you really want to learn more just keep mapping songs you like the way you want to map them, your preferences change over time and with it your mapping skill
if you want more 'formal' lessons you should try applying for the countless mentorship programs for mapping