TV and STB / cable manufacturers 'power on' to the Home Screen by default. We can usually change this to open to either your desired input / app, or to the "last channel." The settings are generally called '[power on' or under 'display.' Please consult the below links or your TV / STB manual or google for specific on your specific device, click on the brands:
All Others, like LG, Insignia, etc:
Use your TV branded remote then look in the settings, then follow the onscreen prompts to set your Input / Source / Power On selection as appropriate (different brands may use their own terminology).
You may need to refer to your manufacturers manual, or google your TV brand, followed by "default input, source or power on settings"