"To match the frame" means to select or choose something that suits or complements the surrounding environment or context. It is all about finding something that fits well with the existing situation or surroundings. Full definition
A group of contemporary prints in matching frames creates a simple display. (idealhome.co.uk)
The designers gathered vintage and new prints of shells, coral, and sea life, then unified each grouping with matching frames. (bhg.com)
These burlap letter framed signs would be great to make on your own, and no need to worry about matching the frames to spell out what you desire. (savingbydesign.com)