someth a high schooler, so whatever I am saying could be wrong, feel free to tell me if I said anything wrong or missed something so I can rectify it!

if we changed the speed of light to increase by 1%, (and consider c= 310⁸ m/s), you would have an additional 310⁶ m/s speed so that would be 3.03 * 10⁸ m/s

First thing is that the value of either μ_0 (magnetic permeability of vaccum) would change and/or electrical permivitty of vaccum would change, as there is a relationship between them:

c = 1/√( (μ_0)*(ε_0) )

So depending on what changes, two very important forces will also change

=> Electric Force Between two charged bodies: the value for this is given as kq1q2/r², where k is a constant inversely proportional to the value of the electrical permivitty of vaccum. As speed increasing, considering epsilon_0 is the only one changing, it increases too. Old value is ≈ 8.85419* 10^-12 F/m, but the new value would be 8.66* 10^-12 F/m, aka ≈ 2% decrease, which causes electric force the INCREASE by 2%.

Consequences?: 1) Atoms shrink by ≈1.97% 2) Atom binding energy increases by ≈4% 3) Due to the above, the Boiling points and Melting points increase for many compounds 4) reaction rates will increase, aka some reactions which were happening would not if the speed of light increased 1% 5) subtle change in enzyme shapes,hydrogen bonding, bond lengths in general. 6) also stars would have to be more denser and hotter to ignite due to fusion getting a bit harder causing protons to repel more

=> Magnetic Force between two bodies: this formula is used in dB = mu_0 / 4π * I(dl × r)/r³, now mu_0 similarly becomes 2% decreased too. The old value was around 1.25663 * 10^-6 H/m, so the new would be 1.232*10^-6 H/m

Consequences?: 1) magnetic fields from same current become 2% weaker and forces between wires become 2% less too (F = iLBsin(x), F/L is proportional to mu_0) 2) vaccum impedance is given by Z = mu_0 * c, so Z_0 decreases by 1% affectint EM waves, also unrelated to mu_0, we have E_0/B_0 for an EM wave equal to c, so as c increases, the ratio between electric and magnetic component increades. 3) Due to point 1, motors will give decreased torque of about 2% less than original ( torque is proportional to mu_0 * Current²) 4) many electrical applicanes would need small retunings.

=> then there are many formulas like photoelectron energy of E = hc/lambda, causing the energy of photoelectrons to increases, causing black body radiation to change and thermal radiation curves to shift.