The Custom Post Templates Plugin allows you to give individual posts their own template. To give the post with ID 3 its own template, add single-3.php to your theme. This plugin can be modified to do a number of additional tricks. Example code is provided if you want to give posts belonging to a certain category their own template.
Published by Ryan Boren
#ActuallyAutistic parent and retired tech worker. Equity literate education, respectfully connected parenting, passion-based learning, indie ed-tech, neurodiversity, social model of disability, design for real life, inclusion, open web, open source. he/they View all posts by Ryan Boren