How can I create a new app with django and the gentella template? I tried to do it with the typical “python3 startapp”.
However, this is the way the app is created in django but it’s not reflected in the template. In the template, there is a configuration section,
in which several options appear to deactivate or activate the applications that we have installed to our liking. However, when installing
in this way, it does not appear in this section in any way. It also does not appear in the side panel of the template.

This command creates django app, not integrate some third part app.

Also I seen gentella template docs and it says

Gentelella Admin is a free to use Bootstrap admin template. 
This template uses the default Bootstrap 4 styles along with a 
variety of powerful jQuery plugins and tools to create a 
powerful framework for creating admin panels or back-end dashboards.

is this the same that you are talking about?
If so then this is just a Bootstrap template that you can manually integrate within django project.

Yes, it is. So, in what way I have to do it?

Have you ever integrated any template with django before?
Because if not than you have to do it manually. i.e by downloading the template code and then use the files within it as per your requirements. This is a whole lot of process, you have to do it by yourself, but if you get stuck somewhere this place is always here to help you.