How to use 12by12 slap of indoor tiles for outdoor?

It would look good on a table. It would also depend on the type of tile.

How about on a countertop for a bar or a backsplash?

Here are some factors to consider:

https://www.thespruce.com/how-to-set-outdoor-patio-tile-2132506

https://www.youtube.com/watch?v=e9ztXu2V04I

Most indoor flooring and some tile won't survive the harsher conditions outside. You might be able to use it in a shed or another enclosed, protected space depending on what material they are.. Good luck and stay safe!

Our contractor did put a ceramic tile in our entryway foyer that is covered. Prior to this we had slate tiles which were torn out due to ineffective drainage leakage.

...a countertop or table -- under a patio cover -- would be great!

Hi Joane. I would put them down in my shed. Or on top of a potting bench.

They could be used as a table top or you could use them beneath potted plants as a "coaster".

here is some help for you

https://www.avalonflooring.com/ideas/blog/best-outdoor-tile

I'd be careful as they could get very slippery when wet

They may not hold up due to weather

Hi Joane, they aren't designed to be used as flooring outdoors, but you can put them on table tops, countertops, or even on a wall for decor, make your yard pretty