The homepage has different sections with different layouts. Each section is capable to display latest posts and you can filter by category, or tag or both.
- Go to the Customizer (WordPress Admin => Appearance => Customize => Home Layout)
- You see four sections ( 0, 1, 2, 3 ).
What you need to setup is the layout, choose one or off the section, after this you can setup a post filter (if you not setup anything than the section will display the latest posts). Just type the name of the category or the tag (not slug, the name like: Tech or Cars).
- Don't forget to save the theme.