You could easily use a 7 wt line on a 5 wt rod…..but it will depend on the line. I’d go with a true 7 wt line based on grain weight.
Years ago before integrated lines became available, it was common for people to make their own shooting head systems that were 2-3 line weights heavier than their rods.
Now that integrated lines are available, you don’t need to make your own or deal with looping heads into running lines or even dealing with the loops.
If you are going to put a 7 wt on your 5 wt, make sure to look at the grain weight. Some lines are already overweighted.
As an example, If you bought a Rio Outbound Short 7 wt line which is an integrated shooting head, the grain weight is 265. 265 grains puts that line between a 9 and 10 weight on the AFTMA standards chart.
A true 7 wt line should be about 185 grains.
A 5 wt Rio Outbound Short is 200 grains which puts it between a 7-8 weight on the standards chart. That would be a good fit for your 5 wt.

It all really depends on how you want to fish. If your intent is to throw 4” streamers like Salmo mentioned in his previous post, an integrated line is the way to go in my opinion on a single handed. There are a lot of them out there now.
I’m heading out to do that right now on my 6 wt.
SF