Please exactly define what you mean talking about "PAL" and "NTSC" because actually none of them exists for digital HD video. Both are terms specifiing a color carrier method for analog (sd) video and unfortunately both terms are kept on using totally different things.

what I knew so far about PAL/NTSC is the uses of it in broadcasting. But for me, I dont really see any big diff in terms of video quality for both PAL/NTSC format since I'm generally making videos online for personal YouTube content and client projects (wedding/MV/Short films)

what I knew so far is PAL produce better color, more lines, hence better video quality over NTSC.

So recording in NTSC and exporting it as PAL change the quality or vice versa?

reason I set my camera in NTSC format is for more video frame rates.

The A6500 only shoots HD and UHD so you're only talking about different frame rates, not color or resolution. But the camera's menu system may still refer to the 30/60/120 fps mode as "NTSC" and the 25/50/100 fps mode as "PAL".

The bit rates are the same for 25/30, 50/60, and 100/120, so at the same video speed the "NTSC" mode gives 16.7% fewer bits per frame, hence slightly lower quality, but there are more frames so you'll get slightly smoother motion. I doubt that much quality loss will be a significant factor, as the camera delivers plenty of bit rate anyway.

There are several factors to consider. How much do you want to slow the video down? How much of it do you want to slow down? What territory are you in and might you ever have other delivery considerations such as DVD or Blu-ray? Do you know whether you want to deliver a more cinematic look (24-25p) or a more video/reality/sporty look (50-60p)?

The A6500 only shoots HD and UHD so you're only talking about different frame rates, not color or resolution. But the camera's menu system may still refer to the 30/60/120 fps mode as "NTSC" and the 25/50/100 fps mode as "PAL".

The bit rates are the same for 25/30, 50/60, and 100/120, so at the same video speed the "NTSC" mode gives 16.7% fewer bits per frame, hence slightly lower quality, but there are more frames so you'll get slightly smoother motion. I doubt that much quality loss will be a significant factor, as the camera delivers plenty of bit rate anyway.

There are several factors to consider. How much do you want to slow the video down? How much of it do you want to slow down? What territory are you in and might you ever have other delivery considerations such as DVD or Blu-ray? Do you know whether you want to deliver a more cinematic look (24-25p) or a more video/reality/sporty look (50-60p)?

Now I understand even more in depth the uses of NTSC/PAL.

I always render my video in this 2 frame rates, either 24 for personal content or 25 for client/assignment content.

Frame rates are not all that interchangeable, and quality is reduced because frames must be synthesized or dropped.

All legacy NTSC source should play on all PAL devices such as disc players. As others said, that goes double for HD and up. No need to go there except as a learning experience.

Blend and Interpolate are crude. If you want to experiment, use a scalpel instead of a hatchet. By that I mean Twixtor or similar.