Do I need to make a boot flashdrive for HD to SSD if using TimeMachine bkup?

Hello all

I had been able to get my computer to finally read my external HD, it’s possible it just needed time to get spinning for me and a tight connection helped too.

My question now is.

I was making a time machine backup in order to upgrade to a Samsung 860 1TB SSD from my original HD , MBP mid 2012- running highSierra still for some reason?

Ive seen how to do all the physical removal and replacing with the SSD... however I’m seeing some people using a “macOS boot flashdrive” and cloning their HD to transfer to the SSD.

I’m wondering cuz I’ve also seen it done without a macOS boot drive plugged in , after the SSD is properly formatted (in recov mode -DU) can I get all my information, AS WELL AS the system macOS to restore to the SSD using the Time Machine option at the top of that disk utility page. Or will I be needing to reformat a flash drive and create a boot macOS for high Sierra I’d guess since I don’t know why but I’m not yet being prompted to download macOS Catalina..??....

but yes. Can the SSD and MBP be completely updated and transferred to the SSD using my (WD 1.5TB w/power supply) external drive and the time machine backup(s) that I’ve recently run, so that everything will be included on the SSD and once I restart after the install, will the TM carry the macOS HS with it.

Thanks very much for any and all help. If I didn’t thank others from the last post I made I apologize, I simply cannot find it. Haha. Sorry.

Thanks again all!! I want to get this SSD into my MBP about 5 years ago so I’m desperately waiting for the proper way to do this.

Dan