I see that there is actually a warning about increased battery drain and higher thermal output. During initial setup, you can see this on the battery settings page. I set up my phone on Saturday, it is now 48 hours later on Monday, and this screenshot was taken just now:
might heat issues only lasted for the first hour or so after I set up the phone, very soon after the data transfer from my old phone to my new phone had completed, and the phone was installing over 120 apps. I haven’t noticed any excessive heat since those few couple of hours of setting up the phone.
I deliberately had the phone on charge the whole time, so that the phone could draw power from the charger, rather than the battery, because draining a lithium battery hard will increase the actual batteries thermal output, further compounding heat issues for the phone itself. Having the phone at 100% charge (or whatever maximum you’ve configured in the battery optimisation settings) and connected to a charger, will keep it cooler during high demand periods.