@hafiz The “Send Record” command just embeds the thumbnail of the attachment, so @Kuovonne’s solution should work for you! 
I’m also curious if embedding the attachment within the body of the email — but using Airtable’s Automations instead of the “Send Record” command — will default to embedding the full size of the attachment. It might also just embed the thumbnail within the body of the email, but I’m not sure.
Of course, if all else fails, you can always access 3 different sizes of the attachment through the web API or the scripting API. Each attachment will give you 3 sizes to choose from: Small, Large, and Full Size.
For a low-code/no-code way of accessing Airtable’s API, you can always turn to Make.com, which gives you point-and-click access to the 3 different attachment sizes. You can see this in the screenshot below:
