EC2 Free 1 year

I apologize, but there seems to be a misunderstanding in your question about the EC2 Free Tier. The EC2 Free Tier does not offer a full year of free usage for any instance size you choose. Instead, it provides a specific offering with limitations:

The Amazon EC2 Free Tier typically includes 750 hours per month of a t2.micro or t3.micro instance (depending on the region) for up to 12 months. This equates to running one instance continuously for a month. These instances generally come with 1 GB of RAM.

You cannot simply exchange this for a larger instance with more RAM (like 8 GB) and still remain within the Free Tier. If you choose a larger instance type, you would be charged according to the regular EC2 pricing, and it would not be part of the Free Tier offering.

The Free Tier is designed to allow users to explore and learn about EC2 with a basic configuration. If you need more powerful instances with more RAM, you would need to pay for those resources, and they would not be covered under the Free Tier regardless of how long you use them.

If you've been using a Free Tier eligible instance and switch to a larger one, you'll start incurring charges based on the new instance type's pricing. The Free Tier period doesn't get shortened; it remains available for the eligible instance types for the full 12 months from the date you opened your AWS account.
Sources
EC2 Instance is extend ? | AWS re:Post
Announcing Amazon EC2 T4g Free Trial Extension | AWS re:Post