All you’ll wind up having to do is pass the entry-specific meta data through to your embedded global html header template as variables in your embed tag. So if you have an embed at the top of your template for the global html header, you could wrap it with an entries tag pair matching what you have below, and feed in entry-level data as variables in the embed. So as a basic example
{exp:channel:entries channel="my_channel" limit="1" orderby="date" sort="desc" disable="pagination|member_data|categories" dynamic="no"}
{embed="embeds/global-html-header" the_entry_seo_title="{entry_seo_title}" the_entry_seo_description="{entry_seo_description}" the_entry_seo_keywords="{entry_seo_keywords}"}
{/exp:channel:entries}
And then subsequently in your global-html-header template, you simply use {embed:the_entry_seo_title} within the template where you would like to place the title. Likewise with description, keywords or whatever else you want to pass through to the header from the entry level.
There are also add-ons that will allow you to do this easier, such as Jumper or Stash, permitting you to use a single entries variable pair (in the page body where is really belongs), declaring these values within but then parsing them OUTSIDE of the entries tag pair, such as in your header embed.
Food for thought! Hope it helps.