The overall combat paradigm of Star Wars is relatively consistent within the movies.

Blaster rifles may be relied upon for up to 10-250 kilojoules per shot.
AT-STs or squad weapons may be relied upon for 1-10 megajoules per shot.
AT-ATs can provide 10-100 megajoules per shot.
Fighter-grade proton torpedos have a yield between 1 and 10 terajoules.
A seismic charge has a yield between 420 terajoules and 4.2 petajoules.
Turbolasers commonly used on ISDs have a per-bolt energy falling between 4.2 terajoules and 420 petajoules (100 megatons). The overall observed rate of fire appears to be relatively low at 23 terawatts - 84 petawatts.

The high end of this range is to be preferred as comparing more reasonably as a fraction of overall power generation. Firepower up to one order of magnitude greater in bombardment situations is possible.

This is seen in TESB most directly, but is suggested throughout the series by the amount of damage seen inflicted by blaster bolts on inanimate and unarmored objects. Armored targets are more difficult to gauge.

AT-STs are seen in detail in ROTJ.

AT-ATs are seen in detail in TESB.

If a proton torpedo contains a proton soup - i.e., hydrogen-1 - in its most dense known form (metallic) and reacted the most energetically (i.e., by fusion) then it could have a total explosive yield of up to ~1 exajoule per cubic meter. Given the size of the actual missile (30 centimeter cone), this gives an absolute maximum theoretical yield of ~1.68 megatons. Ordinary frozen hydrogen filling half the cone would give a yield of up to ~22 kilotons. Modern nuclear warheads in this size range  have been tested at just under 1 terajoule of yield.

Proton torpedos and the small blue bombs dropped by TIE bombers produce incandescent fireballs not far from this range. Even accounting for minor improvements between TPM and later movies, it seems likely that fighter-grade proton torpedos fall in the range of 1-10 terajoules of yield; more than modern devices, but well under the theoretical maximum.

We may suggest that a thermal detonator is, in fact, another compact thermonuclear device. Assuming a similar ratio of volume to yield as a proton torpedo gives us a yield of 0.2-2 terajoules.

The destruction created by proton torpedos appears to exceed the destruction of single bolts from fighter beam weapons.

The seismic charge is discussed in the AOTC Weapons article.

TESB calibrates 50m bolts for us; ROTJ shows 500m bolts. Considering the reasonable range of scalings for the TESB asteroids (up to a bit over half the length of the bolts, or about the same length as the Falcon), per-bolt yields may be as high as 100 megatons. However, observed rates of fire are no more than several bolts per second for the smaller bolts, and one bolt per several seconds for the longer bolts.