Opening from Adobe Camera Raw into Photoshop does not automatically force the file to 8-bit. In ACR you can choose the Photoshop output settings, including opening as 8-bit or 16-bit in a selected color space. In ACR, click the blue workflow text at the bottom of the window to set this.

So while the original RAW file may contain 12- or 14-bit capture data, the Photoshop file you open will be rendered according to your ACR workflow choice—typically 8-bit or 16-bit, not “still RAW.”

If you expect to do significant tonal or exposure editing, 16-bit is usually safer because it preserves more headroom and reduces the chance of banding or posterization. If your edits are minor and the final output is likely 8-bit anyway, working in 8-bit is often fine and faster.

Using duplicate layers and masks in Photoshop can make sense for selective adjustments. Creating multiple ACR versions and blending them later can also work. The key point is that if you want maximum flexibility for heavier edits, open into Photoshop as 16-bit.