When the store for ps3 closes can I still reinstall my games digitally?

According to Sony Support:

We are closing PlayStation™Store on PlayStation®3 consoles on 2nd July 2021 [...]

What features can I use after the closure of PlayStation™Store and purchase functionality on PS3, PS Vita and PSP devices?

Features you will still be able to access:

• You will still be able to re-download and play previously purchased game titles.
• [...]
• You will still be able to re-download and play claimed game titles through PlayStation®Plus as long as you remain a member of the service.

So until Sony decides to change this, you can still redownload and reinstall games purchased on the PlayStation Store to your PS3 (and PS Vita and PSP).

As for how to do that:

How do I access my owned games?
You can download your owned content onto your PS3, PS Vita or PSP device by accessing the Download List on the respective device.