If it was that many colors Ida probably done it in multiple pieces, but since it’s done, spray the whole thing light tan, let it dry, then mask that off and paint the red bricks. I think the window and door trim is a brush job.
Honestly, if you’re careful with how think the red is, you may not need to mortar It if you can leave the tan poking through. Otherwise,
mortar can be done by very diluted light grey acrylic brushed on the whole thing then wiped off. Don’t worry if the mortar takes more than one layer, it’s better to be light than too heavy. Bear in mind how small mortar lines are in scale, you do not need every brick surrounded by an unmistakable square of mortar.
Concrete foundation last. It’s hard to get red off if it bleeds under a tape line.
Thanks for the the input I will give it a try. I have a couple of "reject prints" that I can practice on.