Need Recommendations- ADHD planner/agenda apps for iPad/iPhone

Trying the whole “new year new me”, and I really want to buckle down and get a good agenda/planning system.

Problem-I’m usually old school and prefer to have a physical calendar, but in reflecting on my past patterns, I’m never super satisfied with one, and will always try to find something that will “help me better”, and then along the way I accumulate random pieces of paper, etc. if you know, you know.

About Me- I’m not super tech-y, I like simple. I like something that works. It doesn’t have to be “aesthetic”. I have also been attending counselling for DBT (Dialectical Behaviour Therapy) so if there is any app that incorporates that, it would be a bonus. Again, not being super tech savvy, I’m hoping there exists an app that I can quickly/easily jot down appointments through my phone, and it will automatically synchronize to my iPad ?! This is the year of no unnecessary papers lingering, while also not forgetting appointments.

Kind of looking for a Godsend, but if anyone can share what works for them, I would be super appreciate. I aspire to be (or at least somewhat resemble) that person who just seamlessly does this stuff.

Many thanks !