Is it possible to install a 3/4" valve with compression fitting on soft cooper tubing 3/4" as well? Will it fit? Will it hold? Tank you

Flare it and use a flare fiting

Are you doing water or gas with thgis fitting?

Compression couplings are made for soft copper.
They will hold and are a lot easier to use than flared couplings.
It is getting hard to get flared fittings anymore.
I am assuming this is water pipe.
What type of valve are you using? If it is iron(female threads) you need a compression by 3/4 male iron adaptor at each end of the valve.

We have always used flared fittings on soft copper and compression fittings on hard copper. Compression fittings depend upon something to compress against. Soft copper does not have the ridged surface needed for the ferrule to compress against. If you're running gas lines use flare fittings. If you're running water use hard copper and compression or soldered fittings. Good luck, Tom

I totally agree with Speedball1 and that's why I asked the question regarding water or gas. Ken297 says flared fitting are hard to find? Guess that's why we make our own flare with a flaring tool. Many homeowners do not know what constitutes soft copper/hard copper so confusion gets into the mix when there is a discussion. Go with Tom.