Theoretically if you want to predict the state of product you have to observe the presence of intermolecular forces like Hydrogen bond, ionic interactions, dipole dipole interactions etc. Generally non polar molecules are liquids with low b.p or gases. The presence of intermolecular forces can be predicted using softwares like chemdraw. Also if there is recrystallization is mentioned in procedure (if taken from literature survey) then product will be solid.

The ChemDraw Ultra program has a built-in calculator for calculating melting and boiling points - see the interface with data in the picture in the appendix. There are also several companies that sell programs for determining physical and chemical properties, for example https://www.moldiscovery.com/software/moka/ and https://chemicalize.com/welcome .

Very often, molecules with high molecular mass are solids. This does not mean that they would always solidify readily, even if pure. Sometimes it may take days/weeks for certain molecules to solidify, especially if there are few intermolecular interactions apart from Van der Waals forces and the molecules do not form regular crystals. So, this is why it is important to leave a purified sample in the refrigerator after synthesis for days - weeks (under inert atmosphere, if possible) to see whether a solid will form after some time. Many novel compounds have been listed as oils that may be just reluctant solids.

Interestingly, one polar functionality that is a hydrogen bond donor / hydrogen bond acceptor is not enough to make a substance necessarily a solid at room temperature. Typical examples are amines, alcohols and carboxylic acids, where many of the low weight molecules are liquids. If there are two different functionalities in a molecule that participate in hydrogen bonding and where one is predominantely the hydrogen bond donor and the other the hydrogen bond acceptor and that are spaced relatively close together such as in glycolic acid or in alpha amino acids in general, the substance is often a solid. If the two different functionalities that participate in hydrogen bonding are separated by a longer alkyl chain such as in ricinoleic acid, then the substance can be a liquid (or a solid). Amides are generally solids (except for formamide) as are sulfones as are dicarboxylic acids. Many polar substances that mix with water or are even hygroscopic are solids in the pure (anhydrous) form such as DMSO (18 C), acetamide (81 C) or glycerol (mp. 18 C), when water / moisture is not excluded, we see these molecules as liquids. The same is true for more complicated, novel molecules that after synthesis do not want to solidify (after purification) - try to avoid moisture.