I have done some investigation and found a way to add fonts to the container using Dockerfile. We need to below line docker file:

COPY arial*.ttf c:/windows/fonts/

Below is the updated Dockerfile:

# app image
FROM mcr.microsoft.com/dotnet/framework/runtime:4.8-windowsservercore-ltsc2019  AS BASE
COPY arial*.ttf c:/windows/fonts/
COPY . .
ENTRYPOINT BackgroundService.exe