Sforno on Exodus 6:1/ספורנו על שמות ו׳:א׳

1. עתה תראה, now that you have seen yourself the sin of Pharaoh who has the nerve to hold on to the Israelites with the authority of his office, you will see that he will not only release them voluntarily, but ביד חזקה ישלחם, not only will he release them, but he will be forced to get rid of them post haste due to the problems he will have while they are still in his country.

2וביד חזקה יגרשם מראצו, in contrast with his keeping the Israelites enslaved in his country at this time, he will eventually be forced to expel them by force so that not a single one of them will remain behind.