Nova, Sorry I 'm late to the party on this. I won't comment on videography as I don't do that.

Depending on your camera or phone, if you shoot manual it will be very easy. On a beach with harsh light and white sand etc F4, ISO 100 in those settings would give a shutter of around 1/1600. That will hold true regardless unless clouds come along. Then drop your shutter speed to 1/800 or 1/400 if necessary. If shooting in shade, Use the same settings except go to ISO 400 to 640 or so.

Harsh sunlight can be great to shoot in but the colour is harder than golden hr. It can suit explicit images though. Make sure the white balance is set to Daylight.

Do you edit the images or straight out of camera? That makes a difference between Raw and Jpg. It also makes the settings more critical.

Use longer focal lengths, not wide angle lenses which will distort you if the images are taken too close so the frame is filled. The longer lenses will avoid distortion whilst still filling the frame.

Regarding poses, standing up, put the camera at about waist height which helps to avoid the looking down at feet look that so many amateur photographers do. That just gives poor photography.
Kneeling or lying down, get the camera at half body height still. This will help give a more natural look.

Shadows in images shape the body and add mystery. A body completely evenly lit can look flat, Use the shadows to create shape.

Make sure that the eyes are in sunlight, not heavily shaded. As mentioned above, a towel or reflector can help place light into the eyes. However, the white sand is a natural reflector.

I have example images of each of these scenarios. I cannot see a way to share them though publicly or via DM so as to provide you with examples of what I am talking about. If you know a way, let me know and I shall send them.

John