Mostly I’m missing the large amount and variety of weights and exercise equipment that I can’t fit in my appartment.
I would recommend getting a trainer for a couple sessions. Most gyms will provide them for a small fee.
But generally it’s the same thing. There are different exercises that hit different body parts. Bench press for chest. Squats for legs. Curls for biceps. So on and so forth. People break up their routines in different ways, but you want to cover all the major muscle groups. For each exercise you track how many reps you do of each sets. When it becomes too easy to do 6-10 or so, you increase the weight.
The risk for beginners is that they might try to do too much weight, use poor form and then injure themselves with a sprain or a pull.
Doing 20 squats or curls everytime you walk past those weights, assuming it’s at least a couple of times a day will begin to have some effect. 2 reps at a time is no different than regular day to day activities like standing up or carrying in the groceries. The good reason for going to the gym is that it doesn’t take too long in a structured exercise regime to get good and noticeable results that can be maintained long term with a few home exercises.