I recently bought Crab & Spice | Restaurant wordpress theme. On pages, it shows classic view. I can not make edit on Visual Composer. The theme is compatible with Visual Composer but it does not allow to make changes directly.
Please make sure your theme is gutenbarg (block editor) compatible. If not compatible then you can try to install and active classic editor.
Otherwise please contact your purchased theme and let them know How to Contact your purchased Item Author, theme author will be happy to assist you.