when you create a project in visual studio, you pick the version, so having 7.0 installed has no impact (other than disk space). other tools it may default to 7.0
if there are 7.0 features you want for your new project then I'd use 7.0. But in general I try to stay on the LTS version as you have 6 more months to upgrade.
for example, in November net 8.0 will be released. with 6.0 LTS you will have to Nov 2024 to upgrade. with 7.0 you will have until May 2024 to upgrade. for production, I like to wait a couple months after release to upgrade to a new version. the window is tight for non LTS versions like 7.0.
But if you are doing mobile (Maui) projects, I'd stay on the most current version, as the platforms evolve quickly.