For a desktop Mac or a MacBook? I'll assume a desktop like an iMac.
Just get a decent external USB-3 hard drive. Just a plain hard drive, not an SSD which is overkill. Size is more important than speed here. Go as big as you can. I have recommendations at https://macmost.com/recommendations at the bottom, including the one I am currently using.
For a desktop Mac or a MacBook? I'll assume a desktop like an iMac.
Just get a decent external USB-3 hard drive. Just a plain hard drive, not an SSD which is overkill. Size is more important than speed here. Go as big as you can. I have recommendations at https://macmost.com/recommendations at the bottom, including the one I am currently using.