https://wccftech.com/diablo-ii-resurrected-original-saves/

Diablo II: Resurrected will be fully compatible with the original game's save files, the game producer confirmed recently.

Speaking with IGN Middle East, Game Producer Matthew Cederquist confirmed that players will be able to pick from where they left off in the original and continue playing in the remaster. This isn't completely surprising, considering the remaster doesn't feature any major gameplay change.