Could he just follow previous global trade and minimal fees strategy?

No, as representative and just tool of ruling class (you don't expect finger getting his own though) he must follow interests of ruling class.
And delay with fees on China goods could end up very bad for big remaining US monopolies.
Biggest danger is on smartphones, computer market, wireless equipment markets.
Hence we see closed market for biggest Chinese brands, ban for buying wireless equipment.

What fill follow?

More and wider fees. Slow turn of propaganda machine to form new evil empire, it is slow process.
Next clash will happen in internet where, to sudden surprise, US will start to form barriers and extreme censorship in areas where it is vulnerable.
And, of course, will push "no barriers" agenda where they are much more powerful for now.

But he already declared Greatness archieved..

I have already MADE America Great Again, just look at the markets, jobs, military- setting records, and we will do even better.

Unfortunately such greatness always ends with tens of millions of dead people. Rule of capitalism.