Dear Vandana,

Combining both Landsat 7 and 8 can improve the revisit period from 16 days to 8 days. Although, 7 and 8 have different spatial resolution for the thermal bands, but they can work pretty well to identify urban heat islands or dense construction.

See the following article

Weimin Wang et al., Remote sensing image-based analysis of the urban heat island effect in Shenzhen, China, Physics and Chemistry of the Earth, Parts A/B/C, Volume 110, April 2019, Pages 168-175

Feature selection of various land cover indices for monitoring Surface Heat Island in Tehran city using Landsat 8 imagery , https://rslab.ut.ac.ir/documents/81960329/82017906/FS%20of%20various%20land%20cover%20indices%20for%20monitoring%20SHI%20in%20Tehran%20city%20using%20Landsat%208%20imagery.pdf

Freely maximum resolution thermal data is of 30 m of Landsat series of satellites. However, you can use the fusion technique to enhance the spatial resolution of the thermal data.

See the following article:

Towards LST split-window algorithm FPGA

implementation for CubeSats on-board

computations purposes