Yes, I've always put it to sleep by simply closing the lid.
Although, since I started following this thread, I've noticed that my MPB doesn't sleep for more than a couple of hours at a time.  Infact, I started a separate thread about it here -> 
https://forums.macrumors.com/threads/2018-mbp-doesnt-fully-sleep.2132515
Probably everyone has been too focused on this thread to notice the one I started.
My MBP is a personal-use machine.  It really only gets used in the mornings and in the evenings.
My day job daily driver is a Lenovo P50 running Win 10 Ent.
So, my MBP is awakened in the morning for an hour or so, while I check mail, news, and this forum thread.  Then it goes to sleep by closing the lid.  It is awakened again when I return from work for a few hours while I check mail, news, and this forum thread again.  Then, I put it to sleep by closing the lid before going to bed.
Lately, I've been experimenting with different permutations of sleep conditions (as you'll see that other thread).
I think I connected it to an external monitor once (via TB -to- HDMI dongle), right after I initially set it up, just to see if that would work.  And I connected it to an external USB drive to do a Time Machine Backup once immediately after initial setup.  Otherwise, it's never connected to anything except the AC adapter/charger.