Howdy Danny_f,
That would suggest to me that the 2019 16" is not idle, and doing things in the background. It takes macOS some time when you system is new or freshly installed, to do some "housekeeping" which it will do while your system is idle. Once all of those tasks (such as Spotlight indexing) are complete, it should settle down. Warm to the touch should not be immediately concerning, hot is a different story. My 16" (and 15" for that matter) gets hot under load, between the keyboard and the display, which is by "design." The rest of it may get warm, but never hot.
Good luck!
Rich S.