If I had to amend due to unemployment law is the new refund amount correct or will it be that less what I already received

You generally do not need to amend for Federal.

However, taxpayers would have to file an amended return if they did not originally claim the EITC or other credits, but now are eligible because the [unemployment comp] exclusion changed their income.  These taxpayers may want to review their state tax returns as well.

IRS to recalculate taxes on unemployment benefits; refunds to start in May | Internal Revenue Service

See these re State:

How is my state taxing unemployment income? (intuit.com)

An amended return (Form 1040X) only show the differences.   So, if you originally return indicated a refund of $500 and the amendment shows a $300 refund, you would receive a total of $800.   But as stated above, you don't have to amend if the only difference is the unemployment exclusion.   The IRS is manually processing those returns and issuing additional or adjusted refunds for returns that were filed before the legislative changes were made.   

It is going to take awhile to get 2020 tax returns settled, so be patient while tax refunds pieces are issued over the coming the months.