I owned the 11 6.1 and an AW5 LTE.
With the 11 it was way more convenient, because the 11 is quite big and heavy, bigger than the normal 12 even. But to be honest as a Garmin user I was very dissatisfied with the fitness and sports functions. Way too little for such an expensive watch, I realized it is indeed just a smartwatch.
And charging it everyday was so annoying. I don't know why so many users/reviewers complain about the 12 Mini having so little battery life in their mind but most of them own an Apple Watch which you have to charge each day, sometimes twice if you really used it much with really really bad battery life for even a smartwatch. I don't understand what goes through these peoples minds when doing those statements. DOUBLE STANDARDS.
And I only really used it for LTE and music/podcasts when doing a walk outside and a little more convenient Apple Pay usage. I sold it. And an AW with a bigger iPhone 12 is no comparison to a 12 Mini, I know from experience. If you want a bigger phone ok, but an AW doesn't make a bigger phone seem smaller and you won't use it way less, maybe just a little less in some situations. From what I have read from you everywhere here in this forum, don't do it. But it is your decision. You know I am always on the fence of buying a bigger second phone, I travel a lot and have, atm, much freetime in between, using a bigger phone would make much sense. I just can't. Mini is the best size ever. Not too little, not too big, perfect weight.
PS: To me using those apps like podcasts and music on the watch is very annoying. You can do it but it is not something I Enjoy, very tiny screens, you have to touch on the right point etc. I would first look at an AW from somebody else and check all the apps, I didn't enjoy it, no comparison to an iPhone. But everyone is different.