You can add images to the post and select the size of the image which will be displayed in the front page of the theme. Below the image is shown where you can select the size of the image while adding it in the post.

If you want to show the image in verticle then you have to select the “Vertical Photo” checkbox, and also you can select the position of the page i.e. if you want to show it in left side or in right side

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