Laptop RAM 4GB will it struggle?

[bitmap]

You'll be in a better spot. Just throwing out there that "subtitle transcoding" means the CPU will be transcoding the entire file. If subtitles trigger transcoding, they are burned into the video, which requires transcoding the video as well. So I would recommend avoiding that entirely if possible.

Any time you trigger transcoding, you want a CPU new AND powerful enough (Intel 8th gen+, preferably newer) to use QuickSync effectively in the absence of another method for hardware-accelerated transcoding (i.e., a dedicated GPU). If you avoid transcoding, 8 GB will be fine. If that laptop has an Intel chip newer than ~10th gen, you'll be fine for transcoding.