In principle, what effects does an expansionary fiscal policy have on the exchange rate?

The Biden administration is going to implement a highly expansionary fiscal policy in the United States. This leads us to examine the theoretical effects of fiscal expansion on the exchange rate. Using a fairly traditional model, we show that: Initially, the interest rate increases , the exchange rate appreciates in real terms and foreign trade deteriorates; Then, in the longer term, external debt builds up and the exchange rate depreciates in real terms, which is necessary to stabilise the external debt in the long term. This type of dynamics can now be expected for the dollar, with the exchange rate reversing direction over time.