Global Custom Rows with page specific content

Hi All,
Sorry if this is in the wrong place, new to this forum.
I’m wanting to create a set of custom rows that can be edited globally - can this be done?
The idea is that I would have for example:
Custom Row 1 (Page Header): 100vh splash with 50/50 split, left half h1 over h3, right half text editor
Custom Row 2 (Content Block A): 50vh w/ 50/50 split, fixed background image, left half empty, right half h3 at top, paragraph under it.
Variations of the above to create various content rows for the site.
These custom rows can then be used throughout the site but if I want to change the fundamental structure of the row e.g. for “custom row 2” I want to adjust to a 33/66 split I can do so from a master template that then takes affect on all pages that are based on it.
This feature would be absolutely awesome and is 100% what I need to effectively put my site together.
I know I can create a row template and use those to build the pages but the problem is if I want to adjust a setting in those rows I have to do so on every page that has used the template rather than just adjusting the template. For large sites with mage SEO pages this just isn’t practicle.
All advise welcome.