Then you are in a well designed workplace. Most are not this well organized. I was able to fill the requirements for a higher position in my job so they had to promote me basically because other people could not. Part of being promoted is being able to take on the more technical work in the higher positions. This combines with taking on team work activities. You volunteer to do the things which management does. There are times when the manager is not there because they are on vacation or they have too much work to do.
Also, if you watch closely, there will be professional development opportunities. These usually include some kind of training through your workplace. In addition, there are committees sometimes. These can create connections in the workplace. Being connected makes you more visible and promotable. This includes conference attendance. The objective is to meet people and make your company look good.
There are also programs that offer training. Things like Verizon Skill Forward which gives a year of training for free or if you pay for like administrative certificates. Check to see what your job offers for education credits. How much will they pay for and what will they guarantee if you do the training.
There is also the question of side projects. Some workplaces encourage inventiveness or side projects which show you can do things for the company. There are ways to do things.