Before marriage one needs to know different parameters about the person wants to marry with. these parameters are of two types: one type needs for looking at parts of body that are forbidden for two unmarried. but other type of parameters do not have any need for looking at body. for example if one wants to know if the person participates in mosque for prayer or not, this does not have for looking at body.

In Islam it is recommended to first research about the type of parameters that have no need for looking at body. perhaps during this research the case was canceled. but if all the parameters were OK then they can arrange a meeting for talking which if it is not by intention of enjoying then it is still OK. finally there remains some parameters that need looking at body without a complete Hijab. scholars say if all other parameters are OK and only the looking at body is remained and if the person is serious for marriage in this case there is no problem in looking at body before marriage. but only by serious intention of marriage.

A man married a woman but he did not have been saw her well. then prophet Muhammad SAWW said him: if you have been seen her your relation was stronger and your life was better. (reference of hadith: Wasā'il al-Shīʿa, vol. 14, page 61)

Also Imam Sadiq a.s. said:

[for marriage] if one does not have any abusive intention can look at hair and beauties of the woman. (reference of hadith: Wasā'il al-Shīʿa, vol. 14, page 60)

Fuqaha say 3 terms are required for looking at body before marriage:

1. Looking should not be by intention of enjoying.
2. The marriage is only depending to this look
3. There is no barrier for marriage.

But still some of scholars limit this looking at face and hair.

So two person can know each other by different methods and using intermediate persons like family members without looking each other.

Reference:

View of Islam about knowing boy and girl each other before marriage

Before marriage one needs to know different parameters about the person wants to marry with. These parameters are of two types: one type needs for looking at parts of body that are forbidden for two unmarried. But other type of parameters do not have any need for looking at body. For example if one wants to know if the person participates in mosque for prayer or not, this does not have for looking at body.

In Islam it is recommended to first research about the type of parameters that have no need for looking at body. Perhaps during this research the case was canceled. But if all the parameters were OK then they can arrange a meeting for talking which if it is not by intention of enjoying then it is still OK. Finally there remains some parameters that need looking at body without a complete Hijab. Scholars say if all other parameters are OK and only the looking at body is remained and if the person is serious for marriage in this case there is no problem in looking at body before marriage. But only by serious intention of marriage.

A man married a woman but he did not have been saw her well. Then prophet Muhammad SAWW said him: if you have been seen her your relation was stronger and your life was better. (Reference of hadith: Wasā'il al-Shīʿa, vol. 14, page 61)

Also Imam Sadiq a.s. said:

[for marriage] if one does not have any abusive intention can look at hair and beauties of the woman. (Reference of hadith: Wasā'il al-Shīʿa, vol. 14, page 60)

Fuqaha say 3 terms are required for looking at body before marriage:

1. Looking should not be by intention of enjoying.
2. The marriage is only depending to this look
3. There is no barrier for marriage.

But still some of scholars limit this looking at face and hair.

So two person can know each other by different methods and using intermediate persons like family members without looking each other.

Reference:

View of Islam about knowing boy and girl each other before marriage