Some method to resize the flatpak window's app at start?

Hello to everyone. Sorry for my english
My question is… there is some method to force to resize the window’s app at start of these?
In particular i have Deezer (a flatpak app for listening music) that, at start of it, is too small for me. Everytime. I would have it more big that wath is it at start.
This app its the only that don’t save the window size at closing of it. And i don’t know the cause.
So… exist some method to force it at the start of applications? Maybe a command to add at Deezer launcher.

Thank you very much to everyone for any response.

Edit: i’m using Gnome. Same problem with Xorg or Wayland

If an application does not store the dimensions then there is nothing you can do.

With plasma you may be able to apply window rules for a specific application.

If you really think it is an issue you should create an feature request with the developer(s) of the application.

Thank you for the reply
You were very kind

You could always try an AUR copy of deezer, some I see say enhanced?

Yes, i can try. I suppose i will do it.

After some tests, with deezer-enhanced, it seems to work well. Of course taken by AUR
I thank both for the help
Only, i don’t know if the audio quality is the same of flatpak fork. This, i will hear it after a long listening

I’ve found an alternative solution.
Simply i use the AppImage released from developer on him github page application. Some adjust, and it work perfectly.
The official version present in AUR of this application (flatpak in this case) don’t install himself, so i’ve decided to esclude it.