The mighty Samsung has fallen low and cheap out on many things! Out if the box there is no AKG earhones, S Pen tool, base model start at 128GB compared to Note 10 256GB, 12GB RAM at top tier. The Note 10 had 16GB! Also, the regular Note 20 has a plastic back instead of glass.
Until the phone learns your usage patterns the battery life may suffer. You can check the status of this in Device care.
I'm not seeing an issue with the battery life on my Note 20 Ultra.
Being a regular on these forums, it feels like every new model has "bad battery" posts in the first couple of weeks. I think it's a combination of people actually using their phones more during a new phone honeymoon period, and the usage patterns learning process that takes few days as well. And of course so many of us getting new devices at the same time, making the issue appear larger than it actually is. Once things settle down, these reports fade away.
Also a tip. I recommend setting up a new phone manually and avoid automatic data and settings transfers. It takes more time, but when transferring data from am old phone, it can introduce weird issues and bugs. We just set a new phone up for my mother and did a transfer via smart switch (she doesn't have the knowledge and patience to move everything over herself), and had some very annoying issues with contacts not transferring or syncing to Google. Took me some time to fix.
I have a personal theory that if you transfer your data using one of the automatic transfer methods, your old usage patterns data moves over too which confuses the new device and hurts the battery life for the first couple of weeks. No bases for it, just my guess as I always had a much better experience with a fresh OS with manually re-downloaded apps and stuff like that.
As for settings and battery life, I couldn't get 5G at all on my phone. It took doing a settings reset to get the 5G to work. I used the Samsung sync program (offered during inital set up). I trusted a Samsung sync program would not mess anything up.
I know I like the sync program because it brought over DATA with apps and games!! Its the first time I didn't have to start from scratch with the apps and games.
Bringing over the settings from my Note 9, though, broke the Note 20 (e.g. couldn't get 5G). T-Mobile walked me through doing the reset of the settings. While I lost all my settings, it did fix the problem.
SUGGESTION: Samsung: How about adding a way to list (say on a screen) all the settings changed by the customer from the default. This would also be a great tool for support people, as they would be able to immediately see all the settings changes a customer made to their phone, tablet, laptop, or computer (or appliance).