Well, there is talk of riots and protests but frankly I think most Trump people have learned their lesson watching the insurrectionist being arrested, tried and jailed. I doubt the Trumpies feel the motivation to march on the FBI building or any other government building knowing Trump will desert them in the end. I don't see that kind of loyalty for Trump, not after what happened on Jan 6th.
As far as why the FBI raid?
I wouldn't assume this is a little thing or only seeking documents. My guess is that Donald Trump #1 thinks republicans will control the government come the midterms and #2, that will mean republican states with newly elected republican control can then de-certify the 2020 election thus returning Donald Trump back into the presidency.
This theory could have been well into the planning stage including plans for another insurrection going far beyond that of January 6th. A more organized government coup that would return Trump back into the Whitehouse.
This could be the reason for the FBI raid, to uncover an active and ongoing government overthrow plot planned to take place after the midterms. Succeeding where Jan 6th failed. Whatever the reason of the FBI and the AG, I would bet this goes far beyond Whitehouse documents.
Remember the rule of thumb when it comes to Donald Trump.... whatever terrible thing Trump is suspected of committing, take that and multiply it by 10000, then you begin uncover the true extent of it all.