Yes the uncorrected long sight will stimulate the muscles which focus the eye lens (accommodation) which in turn will stimulate the muscles which pull the eyes closer together, as their actions are linked. This causes an eye to turn in and binocular vision can break down. This should be corrected by the glasses, if it is a fully-accommodative squint.
Sometimes it is partially accommodative, which means there is some squint left over and the eye still turns in even when wearing the glasses, in which case there may be some further measures needed, such as possibly some eye exercises or patching of one eye to stimulate the vision in the eye which turns in, to avoid a condition called amblyopia with reduced vision in the turning-in eye, (sometimes called lazy eye).
If necessary your daughter could be referred to an ophthalmologist ( eye specialist) or orthoptist ( specialist in squints, keeping eyes straight) to help this process along, especially if the optometrist is not able to do this regime. Most of us aren't, as it is quite specialised and we don't see enough cases in everyday practice.
Long sight or short sight rarely goes away even when corrected, that's a bit of an urban myth I'm afraid. However she may need her glasses less as she gets older, such as maybe wearing them for concentrated tasks only when she grows up. It's hard to say, each case varies, and it depends how the prescription changes as she grows. You are right in thinking this is more likely with long sight than short sight, the latter gets worse as the eye grows larger, so much more likely to worsen as they grow up. There is the option of contact lenses, which can be fitted to a well-motivated child from age 9-10.
Keep taking your daughter to her regular eye tests when they send for her and follow your optometrist's advice and all will be well.
You are welcome, no problem, your post caught me after a busy day (and week) at work and I was still on duty !