Themes

Tweentyseventeen child

https://wordpress.org/themes/twentyseventeen/

Twenty Seventeen Preview

https://garyjohnson53.wordpress.com/2018/02/24/child-theme-and-plugin-development-cycle/

Mantra

Mantra Demo
MANTRA Forums

https://www.cryoutcreations.eu/pricing

Theme Modifications

See Appearance - Mantra Settings - to make changes, don't forget to save page setting and Mantra setting (save twice)

With cryout creations plugin you can export and import settings

Theme Page Templates
Default - No Sidebar
Two Columns - Sidebar on the Right (content and sidebar)

.....

Theme Post Templates