I need to get my lazy ass back to the gym before I start getting fat and my A1c goes up. I need something to guide me, otherwise I end up just screwing around and not using my time wisely.

I want an app that basically lays out my routine.

DAY X
1. X reps of X exercise
2. X reps of X exercise
3. ...

DAY X+1...

Any experience with such a thing? Free is, of course, preferred. However, if a paid app has something that makes it worthwhile, I'll consider it, though I'm not particularly interested in any subscription services. Something that suggests exercises wouldn't be bad, although I could also input my own.

I don't think it has a planner to put your next day routine, but I've been using Hevy for a while to enter my workouts.
You can create routines so it prepopulates the exercises, but still takes a little manual entry.

Another good way to exercise is to keep it basic with body weight routines. Pushups, pull-ups if you have access to a bar, sit-ups, walk/jog, squats, planks, jumping jacks, etc....

Most gyms have personal trainers that will help you establish a good workout routine so maybe no need for an app. My workout routine is simple, I workout 5 days a week and I focus on one muscle group a day. One day I'll focus on chest exercises, the next day I'll do legs, the following day I'll do arms, and then shoulders, then abs and after 5 days I've worked each muscle group. You can also add a day or two of cardio by exercising on the treadmill or stationary bike.

I've been doing Arnolds pump club app. Its got suggested exercises, swaps for equipment changes and body weight vs weights etc. It gives you a few different paths depending on if you want to get big or just cut and be healthy. Each one comes with videos with tips and demos, I've found the tips are actually helpful not just generic. It gives you suggested reps etc as you stated.

Also a large mental health and life section that's surprisingly really positive. Its paid but its like a latte a month.

I am up for renewal in Nov and plan to reup. Its been very good and the results have been there for me.

It has a free trial as well, so you can cancel if you'd like.