Can red engineering bricks be used as garden edging?

Yes

An engineering brick will never rot or deteriorate because they are so hard. There are solid ones or the perforated type which you could pay on their edge because they usually have holes through them so couldn't lay them flat. The solid type are more expensive but ideal and will last for years.

Red engineering brick can be used as an edging brick but I aesthetically they aren’t as pleasing as Block paving blocks which are just as strong of if not stronger and keener on the eye. You also have more variety and colours with block pavers. Definitely my choice to go for

Engineering bricks are specifically designed to be dense and impermeable so they absorb less moisture making them less susceptible to frost heave and spalling. They are ideally suited to edging or for decorative effect. Standard stocks are meant to be permeable with the outer face in a cavity wall absorbing the rain and drying out when the weather improves. Engineering bricks can be used as an outer wall but no usually considered cost effective. If you are thinking of using the red engineering bricks with the holes, don't lay them so the holes can fill with water, since water expands when it freezes, causing frost heave and spalling. Standard stock bricks can be used for edging but will not last as long as engineering bricks. Coping stones are probably equivalent to engineering bricks in terms of durability since that is what they are designed for, to shed water away so it does not sit on the surface. As a previous post mentioned, block pavers are similarly dense to engineering bricks if you don't mind the bits that stick out on the sides to tie them together in paving situations. Short answer it depends on personal preference & budget, You get what you pay for basically.