If you are using Strawberry in Linux I can probably help. You would need to install qt6ct, which is the Qt6 Configuration Tool, if it is not already installed in your system.
With this utility you can choose what themes, icons, fonts, etc., that you wish your Qt applications to follow. Strawberry is built using Qt6.
I use Linux Mint, which uses GTK as its graphical toolkit, so this is what I have to do, and it works very well. The app appears as "Qt6 Settings" in my application menu.
If your Strawberry is installed as a Flatpak, I don't think the above method would work. I use Strawberry installed as a system package.
If you are using Windows or Mac, sorry, I don't have any advice. Good luck!