Yes—curled film can usually be flattened safely, but do it gently.

A simple approach is to let the film absorb a bit of moisture, then hold it flat while it dries back to normal room humidity. You can do this by placing it in a high-humidity environment briefly, then putting it in the scanner holder or another flat holder that keeps the strip under light tension until it settles.

A more active method mentioned is to soak the film in a weak water/glycerin solution, then give it a short Photo-Flo rinse and hang it to dry. This can help relax the curl, but use care and handle the film only by the edges.

Why film curls: the film base has multiple gelatin-based layers, and those layers can shrink at different rates as the film dries. The backing layer is meant to balance that, but uneven shrinkage or drying can still produce strong curl. Differences between film stocks can also make some rolls curl more than others.

For storage after scanning, keeping strips in archival sleeves often helps them flatten over time.