@iagtrplyr, @ShawnG,
Gonna make this short (for me). I’m still on our road trip. (Leaving Yellowstone today.)
The only reasons I can think for why the volumes vary among presets are that they’re developed by different folks at Fender, and (perhaps) they’re based on physical amp settings simply transcribed to the digital model; but, they do vary. The Volume control on the amp model is usually the parameter to use to level-match the presets. If there are effects prior to the amp in the signal chain (e.g. a stomp box effect), its volume setting may also be a good place to set the level.
I always keep a personal copy of the presets I use called “MY_xxxx”; so I retain the original preset settings as well as my tweaks. I then copy those presets to my “favorites” slots for live use, so that I don’t overwrite the original presets nor my personal presets. (I only use about 6 presets right now. I also record the settings using my preset templates.).
Volume matching can be mostly done in advance. I use my DAW to get the same approximate dB levels. But, any final tweaks to preset volumes and tones should be done in context (with the band), at performance volumes. I make my changes on the amp’s front panel; then double-press SAVE to save the changes between tests. Of course, you can use the Tone app, too.
After the gig, I review the changes I made to see if it’s something I want to keep, or if the changes were venue-specific (e.g. tonal changes due to room resonance). If I keep the changes, I copy the new settings to my personal presets. If I don’t want to keep the changes, I restore my personal presets to the (live) “favorites” slots.
It may seem a bit OCD, but it works for me.
Hope this helps.
Take care.