I never owned an 8 plus and never kept the XS Max long enough, but in my experience the 12 mini would need a top up in the afternoon (presuming one got up around 630-7am)
It would be good, but was not a full day phone in my use.
Am also in Canada where I dont have the faster 5G spectrum, just the regular one in my area. I would use 5G because that expensive component in the phone is their big selling feature this year, and it is pretty nice but similar to LTE A so far. I did get about 30mbps faster speeds in my area with is a nice bump up. I noticed upload was better, and could send large documents with ease.
But the mini is not a battery champ. It is Not terrible either though. Simply “average”. I found it closer to the SE 2020 in a day’s use, in that it required a top-up, rather than closer to the the 11/Pro or 12/Pro which were full day devices
Is that what the XS max and 8 plus are/were like? The 12 mini reminded me a lot of the regular iPhone X In terms of day to day use, but with 5G it was not quite as good